Cerebrospinal fluid

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Cerebrospinal_fluid

 

Cerebrospinal fluid
The cerebrospinal fluid circulates in the subarachnoid space around the brain and spinal cord, and in the ventricles of the brain.
Image showing the location of CSF highlighting the brain's ventricular system
Details
Identifiers
Latin	liquor cerebrospinalis
Acronym(s)	CSF
MeSH	D002555
TA98	A14.1.01.203
TA2	5388
FMA	20935
Anatomical terminology

Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. It replaces the body fluid found outside the cells of all bilateral animals.

The CSF is produced by specialised ependymal cells in the choroid plexuses of the ventricles of the brain, and absorbed in the arachnoid granulations. There is about 125 mL of CSF at any one time, and about 500 mL is generated every day. CSF acts as a cushion or buffer, providing basic mechanical and immunological protection to the brain inside the skull. CSF also serves a vital function in the cerebral autoregulation of cerebral blood flow.

The CSF occupies the subarachnoid space (between the arachnoid mater and the pia mater) and the ventricular system around and inside the brain and spinal cord. It fills the ventricles of the brain, cisterns, and sulci, as well as the central canal of the spinal cord. There is also a connection from the subarachnoid space to the bony labyrinth of the inner ear via the perilymphatic duct where the perilymph is continuous with the cerebrospinal fluid. The ependymal cells of the choroid plexuses have multiple motile cilia on their apical surfaces that beat to move the CSF through the ventricles.

A sample of CSF can be taken via lumbar puncture. This can reveal the intracranial pressure, as well as indicate diseases including infections of the brain or its surrounding meninges.

Although noted by Hippocrates it was forgotten for centuries. It was discovered in the 18th century by Emanuel Swedenborg. In 1914 Harvey Cushing demonstrated that the CSF was secreted by the choroid plexus.

Structure

Circulation

MRI showing pulsation of CSF

Distribution of CSF

There is about 125–150 mL of CSF at any one time. This CSF circulates within the ventricular system of the brain. The ventricles are a series of cavities filled with CSF. The majority of CSF is produced from within the two lateral ventricles. From here, CSF passes through the interventricular foramina to the third ventricle, then the cerebral aqueduct to the fourth ventricle. From the fourth ventricle, the fluid passes into the subarachnoid space through four openings – the central canal of the spinal cord, the median aperture, and the two lateral apertures. CSF is present within the subarachnoid space, which covers the brain, spinal cord, and stretches below the end of the spinal cord to the sacrum. There is a connection from the subarachnoid space to the bony labyrinth of the inner ear making the cerebrospinal fluid continuous with the perilymph in 93% of people.

CSF moves in a single outward direction from the ventricles, but multidirectionally in the subarachnoid space. Fluid movement is pulsatile, matching the pressure waves generated in blood vessels by the beating of the heart. Some authors dispute this, posing that there is no unidirectional CSF circulation, but cardiac cycle-dependent bi-directional systolic-diastolic to-and-from cranio-spinal CSF movements.

Contents

CSF is derived from blood plasma and is largely similar to it, except that CSF is nearly protein-free compared with plasma and has some different electrolyte levels. Due to the way it is produced, CSF has a higher chloride level than plasma, and an equivalent sodium level.

CSF contains approximately 0.3% plasma proteins, or approximately 15 to 40 mg/dL, depending on sampling site. In general, globular proteins and albumin are in lower concentration in ventricular CSF compared to lumbar or cisternal fluid. This continuous flow into the venous system dilutes the concentration of larger, lipid-insoluble molecules penetrating the brain and CSF. CSF is normally free of red blood cells and at most contains fewer than 5 white blood cells per mm³ (if the cell count of the white blood cells is higher than this, it constitutes pleocytosis).

Development

At around the third week of development, the embryo is a three-layered disc, covered with ectoderm, mesoderm and endoderm. A tube-like formation develops in the midline, called the notochord. The notochord releases extracellular molecules that affect the transformation of the overlying ectoderm into nervous tissue. The neural tube, forming from the ectoderm, contains CSF prior to the development of the choroid plexuses. The open neuropores of the neural tube close after the first month of development, and CSF pressure gradually increases.

As the brain develops, by the fourth week of embryological development three swellings have formed within the embryo around the canal, near where the head will develop. These swellings represent different components of the central nervous system: the prosencephalon, mesencephalon and rhombencephalon. Subarachnoid spaces are first evident around the 32nd day of development near the rhombencephalon; circulation is visible from the 41st day. At this time, the first choroid plexus can be seen, found in the fourth ventricle, although the time at which they first secrete CSF is not yet known.

The developing forebrain surrounds the neural cord. As the forebrain develops, the neural cord within it becomes a ventricle, ultimately forming the lateral ventricles. Along the inner surface of both ventricles, the ventricular wall remains thin, and a choroid plexus develops, producing and releasing CSF. CSF quickly fills the neural canal. Arachnoid villi are formed around the 35th week of development, with arachnoid granulations noted around the 39th, and continuing developing until 18 months of age.

The subcommissural organ secretes SCO-spondin, which forms Reissner's fiber within CSF assisting movement through the cerebral aqueduct. It is present in early intrauterine life but disappears during early development.

Physiology

Function

CSF serves several purposes:

1. Buoyancy: The actual mass of the human brain is about 1400–1500 grams; however, the net weight of the brain suspended in CSF is equivalent to a mass of 25-50 grams. The brain therefore exists in neutral buoyancy, which allows the brain to maintain its density without being impaired by its own weight, which would cut off blood supply and kill neurons in the lower sections without CSF.
2. Protection: CSF protects the brain tissue from injury when jolted or hit, by providing a fluid buffer that acts as a shock absorber from some forms of mechanical injury.
3. Prevention of brain ischemia: The prevention of brain ischemia is aided by decreasing the amount of CSF in the limited space inside the skull. This decreases total intracranial pressure and facilitates blood perfusion.
4. Homeostasis: CSF allows for regulation of the distribution of substances between cells of the brain, and neuroendocrine factors, to which slight changes can cause problems or damage to the nervous system. For example, high glycine concentration disrupts temperature and blood pressure control, and high CSF pH causes dizziness and syncope.
5. Clearing waste: CSF allows for the removal of waste products from the brain, and is critical in the brain's lymphatic system, called the glymphatic system. Metabolic waste products diffuse rapidly into CSF and are removed into the bloodstream as CSF is absorbed. When this goes awry, CSF can be toxic, such as in amyotrophic lateral sclerosis, the commonest form of motor neuron disease.

Production

Comparison of serum and cerebrospinal fluid

Substance	CSF	Serum
Water content (% wt)	99	93
Protein (mg/dL)	35	7000
Glucose (mg/dL)	60	90
Osmolarity (mOsm/L)	295	295
Sodium (mEq/L)	138	138
Potassium (mEq/L)	2.8	4.5
Calcium (mEq/L)	2.1	4.8
Magnesium (mEq/L)	2.0–2.5	1.7
Chloride (mEq/L)	119	102
pH	7.33	7.41

The brain produces roughly 500 mL of cerebrospinal fluid per day, at a rate of about 25 mL an hour. This transcellular fluid is constantly reabsorbed, so that only 125–150 mL is present at any one time.

CSF volume is higher on a mL/kg basis in children compared to adults. Infants have a CSF volume of 4 mL/kg, children have a CSF volume of 3 mL/kg, and adults have a CSF volume of 1.5–2 mL/kg. A high CSF volume is why a larger dose of local anesthetic, on a mL/kg basis, is needed in infants. Additionally, the larger CSF volume may be one reason as to why children have lower rates of postdural puncture headache.

Most (about two-thirds to 80%) of CSF is produced by the choroid plexus. The choroid plexus is a network of blood vessels present within sections of the four ventricles of the brain. It is present throughout the ventricular system except for the cerebral aqueduct, and the frontal and occipital horns of the lateral ventricles. CSF is also produced by the single layer of column-shaped ependymal cells which line the ventricles; by the lining surrounding the subarachnoid space; and a small amount directly from the tiny spaces surrounding blood vessels around the brain.

CSF is produced by the choroid plexus in two steps. Firstly, a filtered form of plasma moves from fenestrated capillaries in the choroid plexus into an interstitial space, with movement guided by a difference in pressure between the blood in the capillaries and the interstitial fluid. This fluid then needs to pass through the epithelium cells lining the choroid plexus into the ventricles, an active process requiring the transport of sodium, potassium and chloride that draws water into CSF by creating osmotic pressure. Unlike blood passing from the capillaries into the choroid plexus, the epithelial cells lining the choroid plexus contain tight junctions between cells, which act to prevent most substances flowing freely into CSF. Cilia on the apical surfaces of the ependymal cells beat to help transport the CSF.

Water and carbon dioxide from the interstitial fluid diffuse into the epithelial cells. Within these cells, carbonic anhydrase converts the substances into bicarbonate and hydrogen ions. These are exchanged for sodium and chloride on the cell surface facing the interstitium. Sodium, chloride, bicarbonate and potassium are then actively secreted into the ventricular lumen. This creates osmotic pressure and draws water into CSF, facilitated by aquaporins. Chloride, with a negative charge, moves with the positively charged sodium, to maintain electroneutrality. Potassium and bicarbonate are also transported out of CSF. As a result, CSF contains a higher concentration of sodium and chloride than blood plasma, but less potassium, calcium and glucose and protein. Choroid plexuses also secrete growth factors, iodine, vitamins B1, B12, C, folate, beta-2 microglobulin, arginine vasopressin and nitric oxide into CSF. A Na-K-Cl cotransporter and Na/K ATPase found on the surface of the choroid endothelium, appears to play a role in regulating CSF secretion and composition.

Orešković and Klarica hypothesise that CSF is not primarily produced by the choroid plexus, but is being permanently produced inside the entire CSF system, as a consequence of water filtration through the capillary walls into the interstitial fluid of the surrounding brain tissue, regulated by AQP-4.

There are circadian variations in CSF secretion, with the mechanisms not fully understood, but potentially relating to differences in the activation of the autonomic nervous system over the course of the day.

Choroid plexus of the lateral ventricle produces CSF from the arterial blood provided by the anterior choroidal artery. In the fourth ventricle, CSF is produced from the arterial blood from the anterior inferior cerebellar artery (cerebellopontine angle and the adjacent part of the lateral recess), the posterior inferior cerebellar artery (roof and median opening), and the superior cerebellar artery.

Reabsorption

CSF returns to the vascular system by entering the dural venous sinuses via arachnoid granulations. These are outpouchings of the arachnoid mater into the venous sinuses around the brain, with valves to ensure one-way drainage. This occurs because of a pressure difference between the arachnoid mater and venous sinuses. CSF has also been seen to drain into lymphatic vessels, particularly those surrounding the nose via drainage along the olfactory nerve through the cribriform plate. The pathway and extent are currently not known, but may involve CSF flow along some cranial nerves and be more prominent in the neonate. CSF turns over at a rate of three to four times a day. CSF has also been seen to be reabsorbed through the sheathes of cranial and spinal nerve sheathes, and through the ependyma.

Regulation

The composition and rate of CSF generation are influenced by hormones and the content and pressure of blood and CSF. For example, when CSF pressure is higher, there is less of a pressure difference between the capillary blood in choroid plexuses and CSF, decreasing the rate at which fluids move into the choroid plexus and CSF generation. The autonomic nervous system influences choroid plexus CSF secretion, with activation of the sympathetic nervous system decreasing secretion and the parasympathetic nervous system increasing it. Changes in the pH of the blood can affect the activity of carbonic anhydrase, and some drugs (such as frusemide, acting on the Na-Cl cotransporter) have the potential to impact membrane channels.

Clinical significance

Pressure

CSF pressure, as measured by lumbar puncture, is 10–18 cmH₂O (8–15 mmHg or 1.1–2 kPa) with the patient lying on the side and 20–30 cmH₂O (16–24 mmHg or 2.1–3.2 kPa) with the patient sitting up. In newborns, CSF pressure ranges from 8 to 10 cmH₂O (4.4–7.3 mmHg or 0.78–0.98 kPa). Most variations are due to coughing or internal compression of jugular veins in the neck. When lying down, the CSF pressure as estimated by lumbar puncture is similar to the intracranial pressure.

Hydrocephalus is an abnormal accumulation of CSF in the ventricles of the brain. Hydrocephalus can occur because of obstruction of the passage of CSF, such as from an infection, injury, mass, or congenital abnormality. Hydrocephalus without obstruction associated with normal CSF pressure may also occur. Symptoms can include problems with gait and coordination, urinary incontinence, nausea and vomiting, and progressively impaired cognition. In infants, hydrocephalus can cause an enlarged head, as the bones of the skull have not yet fused, seizures, irritability and drowsiness. A CT scan or MRI scan may reveal enlargement of one or both lateral ventricles, or causative masses or lesions, and lumbar puncture may be used to demonstrate and in some circumstances relieve high intracranial pressure. Hydrocephalus is usually treated through the insertion of a shunt, such as a ventriculo-peritoneal shunt, which diverts fluid to another part of the body.

Idiopathic intracranial hypertension is a condition of unknown cause characterized by a rise in CSF pressure. It is associated with headaches, double vision, difficulties seeing, and a swollen optic disc. It can occur in association with the use of Vitamin A and tetracycline antibiotics, or without any identifiable cause at all, particularly in younger obese women. Management may include ceasing any known causes, a carbonic anhydrase inhibitor such as acetazolamide, repeated drainage via lumbar puncture, or the insertion of a shunt such as a ventriculoperitoneal shunt.

CSF leak

CSF can leak from the dura as a result of different causes such as physical trauma or a lumbar puncture, or from no known cause when it is termed a spontaneous cerebrospinal fluid leak. It is usually associated with intracranial hypotension: low CSF pressure. It can cause headaches, made worse by standing, moving and coughing, as the low CSF pressure causes the brain to "sag" downwards and put pressure on its lower structures. If a leak is identified, a beta-2 transferrin test of the leaking fluid, when positive, is highly specific and sensitive for the detection for CSF leakage. Medical imaging such as CT scans and MRI scans can be used to investigate for a presumed CSF leak when no obvious leak is found but low CSF pressure is identified. Caffeine, given either orally or intravenously, often offers symptomatic relief. Treatment of an identified leak may include injection of a person's blood into the epidural space (an epidural blood patch), spinal surgery, or fibrin glue.

Lumbar puncture

Vials containing human cerebrospinal fluid.

CSF can be tested for the diagnosis of a variety of neurological diseases, usually obtained by a procedure called lumbar puncture. Lumbar puncture is carried out under sterile conditions by inserting a needle into the subarachnoid space, usually between the third and fourth lumbar vertebrae. CSF is extracted through the needle, and tested. About one third of people experience a headache after lumbar puncture, and pain or discomfort at the needle entry site is common. Rarer complications may include bruising, meningitis or ongoing post lumbar-puncture leakage of CSF.

Testing often includes observing the colour of the fluid, measuring CSF pressure, and counting and identifying white and red blood cells within the fluid; measuring protein and glucose levels; and culturing the fluid. The presence of red blood cells and xanthochromia may indicate subarachnoid hemorrhage; whereas central nervous system infections such as meningitis, may be indicated by elevated white blood cell levels. A CSF culture may yield the microorganism that has caused the infection, or PCR may be used to identify a viral cause. Investigations to the total type and nature of proteins reveal point to specific diseases, including multiple sclerosis, paraneoplastic syndromes, systemic lupus erythematosus, neurosarcoidosis, cerebral angiitis; and specific antibodies such as Aquaporin 4 may be tested for to assist in the diagnosis of autoimmune conditions. A lumbar puncture that drains CSF may also be used as part of treatment for some conditions, including idiopathic intracranial hypertension and normal pressure hydrocephalus.

Lumbar puncture can also be performed to measure the intracranial pressure, which might be increased in certain types of hydrocephalus. However, a lumbar puncture should never be performed if increased intracranial pressure is suspected due to certain situations such as a tumour, because it can lead to fatal brain herniation.

Anaesthesia and chemotherapy

Some anaesthetics and chemotherapy are injected intrathecally into the subarachnoid space, where they spread around CSF, meaning substances that cannot cross the blood-brain barrier can still be active throughout the central nervous system. Baricity refers to the density of a substance compared to the density of human cerebrospinal fluid and is used in regional anesthesia to determine the manner in which a particular drug will spread in the intrathecal space.

History

Various comments by ancient physicians have been read as referring to CSF. Hippocrates discussed "water" surrounding the brain when describing congenital hydrocephalus, and Galen referred to "excremental liquid" in the ventricles of the brain, which he believed was purged into the nose. But for some 16 intervening centuries of ongoing anatomical study, CSF remained unmentioned in the literature. This is perhaps because of the prevailing autopsy technique, which involved cutting off the head, thereby removing evidence of CSF before the brain was examined.

The modern rediscovery of CSF is credited to Emanuel Swedenborg. In a manuscript written between 1741 and 1744, unpublished in his lifetime, Swedenborg referred to CSF as "spirituous lymph" secreted from the roof of the fourth ventricle down to the medulla oblongata and spinal cord. This manuscript was eventually published in translation in 1887.

Albrecht von Haller, a Swiss physician and physiologist, made note in his 1747 book on physiology that the "water" in the brain was secreted into the ventricles and absorbed in the veins, and when secreted in excess, could lead to hydrocephalus. Francois Magendie studied the properties of CSF by vivisection. He discovered the foramen Magendie, the opening in the roof of the fourth ventricle, but mistakenly believed that CSF was secreted by the pia mater.

Thomas Willis (noted as the discoverer of the circle of Willis) made note of the fact that the consistency of CSF is altered in meningitis. In 1869 Gustav Schwalbe proposed that CSF drainage could occur via lymphatic vessels.

In 1891, W. Essex Wynter began treating tubercular meningitis by removing CSF from the subarachnoid space, and Heinrich Quincke began to popularize lumbar puncture, which he advocated for both diagnostic and therapeutic purposes. In 1912, a neurologist William Mestrezat gave the first accurate description of the chemical composition of CSF. In 1914, Harvey W. Cushing published conclusive evidence that CSF is secreted by the choroid plexus.

Other animals

During phylogenesis, CSF is present within the neuraxis before it circulates. The CSF of Teleostei fish is contained within the ventricles of the brains, but not in a nonexistent subarachnoid space. In mammals, where a subarachnoid space is present, CSF is present in it. Absorption of CSF is seen in amniotes and more complex species, and as species become progressively more complex, the system of absorption becomes progressively more enhanced, and the role of spinal epidural veins in absorption plays a progressively smaller and smaller role.

The amount of cerebrospinal fluid varies by size and species. In humans and other mammals, cerebrospinal fluid, produced, circulating, and reabsorbed in a similar manner to humans, and with a similar function, turns over at a rate of 3–5 times a day. Problems with CSF circulation leading to hydrocephalus occur in other animals.

Precocious puberty

From Wikipedia, the free encyclopedia

Precocious puberty
Other names	Early puberty
Precocious puberty is the early development of phenotypical sex organs before the age of 8 in girls and 9 in boys.
Specialty	Gynecology, endocrinology
Causes	Idiopathic, brain damage, brain tumor

In medicine, precocious puberty is puberty occurring at an unusually early age. In most cases, the process is normal in every aspect except the unusually early age and simply represents a variation of normal development. In a minority of children with precocious puberty, the early development is triggered by a disease such as a tumor or injury of the brain. Even when there is no disease, unusually early puberty can have adverse effects on social behavior and psychological development, can reduce adult height potential, and may shift some lifelong health risks. Central precocious puberty can be treated by suppressing the pituitary hormones that induce sex steroid production. The opposite condition is delayed puberty.

The term is used with several slightly different meanings that are usually apparent from the context. In its broadest sense, and often simplified as early puberty, "precocious puberty" sometimes refers to any physical sex hormone effect, due to any cause, occurring earlier than the usual age, especially when it is being considered as a medical problem. Stricter definitions of "precocity" may refer only to central puberty starting before a statistically specified age based on percentile in the population (e.g., 2.5 standard deviations below the population mean), on expert recommendations of ages at which there is more than a negligible chance of discovering an abnormal cause, or based on opinion as to the age at which early puberty may have adverse effects. A common definition for medical purposes is onset before 8 years in girls or 9 years in boys.

History

Pubertas praecox is the Latin term used by physicians from the 1790s onward. Various theories and inferences on pubertal (menstrual, procreative) timing are attested since ancient times, which well into early modernity were explained on the basis of temperamental, humoral and complexional theory, and increasingly specifically, general or local "plethora". Endocrinological (hormonal) theories and discoveries are a twentieth-century development.

Causes

Early pubic hair, breast, or genital development may result from natural early maturation or from several other conditions.

Central

If the cause can be traced to the hypothalamus or pituitary, the cause is considered central. Other names for this type are complete or true precocious puberty.

Causes of central precocious puberty can include:

• damage to the inhibitory system of the brain (due to infection, trauma, or irradiation)
• hypothalamic hamartoma produces pulsatile gonadotropin-releasing hormone (GnRH)
• Langerhans cell histiocytosis
• McCune–Albright syndrome

Central precocious puberty can also be caused by brain tumors, infection (most commonly tuberculous meningitis, especially in developing countries), trauma, hydrocephalus, and Angelman syndrome. Precocious puberty is associated with advancement in bone age, which leads to early fusion of epiphyses, thus resulting in reduced final height and short stature.

Adrenocortical oncocytomas are rare with mostly benign and nonfunctioning tumors. There have been only three cases of functioning adrenocortical oncocytoma that have been reported up until 2013. Children with adrenocortical oncocytomas will present with "premature pubarche, clitoromegaly, and increased serum dehydroepiandrosterone sulfate and testosterone" which are some of the presentations associated with precocious puberty.

Precocious puberty in girls begins before the age of 8. The youngest mother on record is Lina Medina, who gave birth at the age of either 5 years, 7 months and 17 days or 6 years 5 months as mentioned in another report.

"Central precocious puberty (CPP) was reported in some patients with suprasellar arachnoid cysts (SAC), and SCFE (slipped capital femoral epiphysis) occurs in patients with CPP because of rapid growth and changes of growth hormone secretion."

If no cause can be identified, it is considered idiopathic or constitutional.

Peripheral

Secondary sexual development induced by sex steroids from other abnormal sources is referred to as peripheral precocious puberty or precocious pseudopuberty. It typically presents as a severe form of disease with children. Symptoms are usually as a sequelae from adrenal insufficiency (because of 21-hydroxylase deficiency or 11-beta hydroxylase deficiency, the former being more common), which includes but is not limited to hypertension, hypotension, electrolyte abnormalities, ambiguous genitalia in females, signs of virilization in females. Blood tests will typically reveal high level of androgens with low levels of cortisol.

Causes can include:

• Endogenous sources
  • Gonadal tumors (such as arrhenoblastoma)
  • Adrenal tumors
  • Germ cell tumor
  • Congenital adrenal hyperplasia
  • McCune–Albright syndrome
  • Familial male-limited precocious puberty (testotoxicosis)
• Exogenous hormones
  • Environmental exogenous hormones
  • As treatment for another condition

Isosexual and heterosexual

Generally, patients with precocious puberty develop phenotypically appropriate secondary sexual characteristics. This is called isosexual precocity.

In some cases, a patient may develop characteristics of the opposite sex. For example, a male may develop breasts and other feminine characteristics, while a female may develop a deepened voice and facial hair. This is called heterosexual or contrasexual precocity. It is very rare in comparison to isosexual precocity and is usually the result of unusual circumstances. As an example, children with a very rare genetic condition called aromatase excess syndrome- in which exceptionally high circulating levels of estrogen are present- usually develop precocious puberty. Males and females are hyper-feminized by the syndrome. The "opposite" case would be the hyper-masculinisation of both male and female patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, in which there is an excess of androgens. Thus, in the aromatase excess syndrome the precocious puberty is isosexual in females and heterosexual in males, whilst in the CAH it's isosexual in males and heterosexual in females.

Effects of precocious puberty

Research

Although the causes of early puberty are still somewhat unclear, girls who have a high-fat diet and are not physically active or are obese are more likely to physically mature earlier. "Obese girls, defined as at least 10 kilograms (22 pounds) overweight, had an 80 percent chance of developing breasts before their ninth birthday and starting menstruation before age 12 – the western average for menstruation is about 12.7 years." In addition to diet and exercise habits, exposure to chemicals that mimic estrogen (known as xenoestrogens) is another possible cause of early puberty in girls. Bisphenol A, a xenoestrogen found in hard plastics, has been shown to affect sexual development. "Factors other than obesity, however, perhaps genetic and/or environmental ones, are needed to explain the higher prevalence of early puberty in black versus white girls." While more girls are increasingly entering puberty at younger ages, new research indicates that some boys are actually starting later (delayed puberty). "Increasing rates of obese and overweight children in the United States may be contributing to a later onset of puberty in boys, say researchers at the University of Michigan Health System."

High levels of beta-hCG in serum and cerebrospinal fluid observed in a 9-year-old boy suggest a pineal gland tumor. The tumor is called a chorionic gonadotropin secreting pineal tumor. Radiotherapy and chemotherapy reduced tumor and beta-hCG levels normalized.

In a study using neonatal melatonin on rats, results suggest that elevated melatonin could be responsible for some cases of early puberty.

Familial cases of idiopathic central precocious puberty (ICPP) have been reported, leading researchers to believe there are specific genetic modulators of ICPP. Mutations in genes such as LIN28, and LEP and LEPR, which encode leptin and the leptin receptor, have been associated with precocious puberty. The association between LIN28 and puberty timing was validated experimentally in vivo, when it was found that mice with ectopic over-expression of LIN28 show an extended period of pre-pubertal growth and a significant delay in puberty onset.

Mutations in the kisspeptin (KISS1) and its receptor, KISS1R (also known as GPR54), involved in GnRH secretion and puberty onset, are also thought to be the cause for ICPP However, this is still a controversial area of research, and some investigators found no association of mutations in the LIN28 and KISS1/KISS1R genes to be the common cause underlying ICPP.

The gene MKRN3, which is a maternally imprinted gene, was first cloned by Jong et al. in 1999. MKRN3 was originally named Zinc finger protein 127. It is located on human chromosome 15 on the long arm in the Prader-Willi syndrome critical region2, and has since been identified as a cause of premature sexual development or CPP. The identification of mutations in MKRN3 leading to sporadic cases of CPP has been a significant contribution to better understanding the mechanism of puberty. MKRN3 appears to act as a "brake" on the central hypothalamic-pituitary access. Thus, loss of function mutations of the protein allow early activation of the GnRH pathway and cause phenotypic CPP. Patients with a MKRN3 mutation all display the classic signs of CCP including early breast and testes development, increased bone aging and elevated hormone levels of GnRH and LH.

Diagnosis

Studies indicate that breast development in girls and the appearance of pubic hair in both girls and boys are starting earlier than in previous generations. As a result, "early puberty" in children as young as 9 and 10 is no longer considered abnormal, particularly with girls. Although it is not considered as abnormal, it may be upsetting to parents and can be harmful to children who mature physically at a time when they are immature mentally.

No age reliably separates normal from abnormal processes in children, but the following age thresholds for evaluation are thought to minimize the risk of missing a significant medical problem:

• Breast development in boys before appearance of pubic hair or testicular enlargement
• Pubic hair or genital enlargement (gonadarche) in boys with onset before 9.5 years
• Pubic hair (pubarche) before 8 or breast development (thelarche) in girls with onset before 7 years
• Menstruation (menarche) in girls before 10 years

Medical evaluation is sometimes necessary to recognize the few children with serious conditions from the majority who have entered puberty early but are still medically normal. Early sexual development warrants evaluation because it may:

• induce early bone maturation and reduce eventual adult height
• indicate the presence of a tumour or other serious problem
• cause the child, particularly a girl, to become an object of adult sexual interest.

Treatment

One possible treatment is with anastrozole. Histrelin, triptorelin, or leuprorelin, any GnRH agonists, may be used. Non-continuous usage of GnRH agonists stimulates the pituitary gland to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). However, when used regularly, GnRH agonists cause a decreased release of FSH and LH. Prolonged use has a risk of causing osteoporosis. After stopping GnRH agonists, pubertal changes resume within 3 to 12 months.

Prognosis

Early puberty is posited to put girls at higher risk of sexual abuse; however, a causal relationship is, as yet, inconclusive. Early puberty also puts girls at a higher risk for teasing or bullying, mental health disorders and short stature as adults. Helping children control their weight is suggested to help delay puberty. Early puberty additionally puts girls at a "far greater" risk for breast cancer later in life. Girls as young as 8 are increasingly starting to menstruate, develop breasts and grow pubic and underarm hair; these "biological milestones" typically occurred only at 13 or older in the past. African-American girls are especially prone to early puberty. There are theories debating the trend of early puberty, but the exact causes are not known.

Though boys face fewer problems upon early puberty than girls, early puberty is not always positive for boys; early sexual maturation in boys can be accompanied by increased aggressiveness due to the surge of hormones that affect them. Because they appear older than their peers, pubescent boys may face increased social pressure to conform to adult norms; society may view them as more emotionally advanced, although their cognitive and social development may lag behind their appearance. Studies have shown that early maturing boys are more likely to be sexually active and are more likely to participate in risky behaviors.

 

Birth control

From Wikipedia, the free encyclopedia

Birth control
A package of birth control pills
Other names	Contraception, fertility control
MeSH	D003267

Birth control, also known as contraception, anticonception, and fertility control, is a method or device used to prevent pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth control only became available in the 20th century. Planning, making available, and using birth control is called family planning. Some cultures limit or discourage access to birth control because they consider it to be morally, religiously, or politically undesirable.

The World Health Organization and United States Centers for Disease Control and Prevention provide guidance on the safety of birth control methods among women with specific medical conditions. The most effective methods of birth control are sterilization by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable birth control. This is followed by a number of hormone-based methods including oral pills, patches, vaginal rings, and injections. Less effective methods include physical barriers such as condoms, diaphragms and birth control sponges and fertility awareness methods. The least effective methods are spermicides and withdrawal by the male before ejaculation. Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them. Safe sex practices, such as with the use of male or female condoms, can also help prevent sexually transmitted infections. Other methods of birth control do not protect against sexually transmitted diseases. Emergency birth control can prevent pregnancy if taken within 72 to 120 hours after unprotected sex. Some argue not having sex is also a form of birth control, but abstinence-only sex education may increase teenage pregnancies if offered without birth control education, due to non-compliance.

In teenagers, pregnancies are at greater risk of poor outcomes. Comprehensive sex education and access to birth control decreases the rate of unwanted pregnancies in this age group. While all forms of birth control can generally be used by young people, long-acting reversible birth control such as implants, IUDs, or vaginal rings are more successful in reducing rates of teenage pregnancy. After the delivery of a child, a woman who is not exclusively breastfeeding may become pregnant again after as few as four to six weeks. Some methods of birth control can be started immediately following the birth, while others require a delay of up to six months. In women who are breastfeeding, progestin-only methods are preferred over combined oral birth control pills. In women who have reached menopause, it is recommended that birth control be continued for one year after the last period.

About 222 million women who want to avoid pregnancy in developing countries are not using a modern birth control method. Birth control use in developing countries has decreased the number of deaths during or around the time of pregnancy by 40% (about 270,000 deaths prevented in 2008) and could prevent 70% if the full demand for birth control were met. By lengthening the time between pregnancies, birth control can improve adult women's delivery outcomes and the survival of their children. In the developing world, women's earnings, assets, and weight, as well as their children's schooling and health, all improve with greater access to birth control. Birth control increases economic growth because of fewer dependent children, more women participating in the workforce, and less use of scarce resources.

Methods

Birth control methods include barrier methods, hormonal birth control, intrauterine devices (IUDs), sterilization, and behavioral methods. They are used before or during sex while emergency contraceptives are effective for up to five days after sex. Effectiveness is generally expressed as the percentage of women who become pregnant using a given method during the first year, and sometimes as a lifetime failure rate among methods with high effectiveness, such as tubal ligation.

The most effective methods are those that are long acting and do not require ongoing health care visits. Surgical sterilization, implantable hormones, and intrauterine devices all have first-year failure rates of less than 1%. Hormonal contraceptive pills, patches or vaginal rings, and the lactational amenorrhea method (LAM), if adhered to strictly, can also have first-year (or for LAM, first-6-month) failure rates of less than 1%. With typical use, first-year failure rates are considerably high, at 9%, due to inconsistent use. Other methods such as condoms, diaphragms, and spermicides have higher first-year failure rates even with perfect usage. The American Academy of Pediatrics recommends long acting reversible birth control as first line for young individuals.

While all methods of birth control have some potential adverse effects, the risk is less than that of pregnancy. After stopping or removing many methods of birth control, including oral contraceptives, IUDs, implants and injections, the rate of pregnancy during the subsequent year is the same as for those who used no birth control.

For individuals with specific health problems, certain forms of birth control may require further investigations. For women who are otherwise healthy, many methods of birth control should not require a medical exam—including birth control pills, injectable or implantable birth control, and condoms. For example, a pelvic exam, breast exam, or blood test before starting birth control pills does not appear to affect outcomes. In 2009, the World Health Organization (WHO) published a detailed list of medical eligibility criteria for each type of birth control.

Hormonal

Hormonal contraception is available in a number of different forms, including oral pills, implants under the skin, injections, patches, IUDs and a vaginal ring. They are currently available only for women, although hormonal contraceptives for men have been and are being clinically tested. There are two types of oral birth control pills, the combined oral contraceptive pills (which contain both estrogen and a progestin) and the progestogen-only pills (sometimes called minipills). If either is taken during pregnancy, they do not increase the risk of miscarriage nor cause birth defects. Both types of birth control pills prevent fertilization mainly by inhibiting ovulation and thickening cervical mucus. They may also change the lining of the uterus and thus decrease implantation. Their effectiveness depends on the user's adherence to taking the pills.

Combined hormonal contraceptives are associated with a slightly increased risk of venous and arterial blood clots. Venous clots, on average, increase from 2.8 to 9.8 per 10,000 women years which is still less than that associated with pregnancy. Due to this risk, they are not recommended in women over 35 years of age who continue to smoke. Due to the increased risk, they are included in decision tools such as the DASH score and PERC rule used to predict the risk of blood clots.

The effect on sexual desire is varied, with increase or decrease in some but with no effect in most. Combined oral contraceptives reduce the risk of ovarian cancer and endometrial cancer and do not change the risk of breast cancer. They often reduce menstrual bleeding and painful menstruation cramps. The lower doses of estrogen released from the vaginal ring may reduce the risk of breast tenderness, nausea, and headache associated with higher dose estrogen products.

Progestin-only pills, injections and intrauterine devices are not associated with an increased risk of blood clots and may be used by women with a history of blood clots in their veins. In those with a history of arterial blood clots, non-hormonal birth control or a progestin-only method other than the injectable version should be used. Progestin-only pills may improve menstrual symptoms and can be used by breastfeeding women as they do not affect milk production. Irregular bleeding may occur with progestin-only methods, with some users reporting no periods. The progestins drospirenone and desogestrel minimize the androgenic side effects but increase the risks of blood clots and are thus not first line. The perfect use first-year failure rate of injectable progestin is 0.2%; the typical use first failure rate is 6%.

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  Three varieties of birth control pills in calendar oriented packaging

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  Birth control pills

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  A transdermal contraceptive patch

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  A NuvaRing vaginal ring

Barrier

Barrier contraceptives are devices that attempt to prevent pregnancy by physically preventing sperm from entering the uterus. They include male condoms, female condoms, cervical caps, diaphragms, and contraceptive sponges with spermicide.

Globally, condoms are the most common method of birth control. Male condoms are put on a man's erect penis and physically block ejaculated sperm from entering the body of a sexual partner during intercourse and fellatio. Modern condoms are most often made from latex, but some are made from other materials such as polyurethane, or lamb's intestine. Female condoms are also available, most often made of nitrile, latex or polyurethane. Male condoms have the advantage of being inexpensive, easy to use, and have few adverse effects. Making condoms available to teenagers does not appear to affect the age of onset of sexual activity or its frequency. In Japan, about 80% of couples who are using birth control use condoms, while in Germany this number is about 25%, and in the United States it is 18%.

Male condoms and the diaphragm with spermicide have typical use first-year failure rates of 18% and 12%, respectively. With perfect use condoms are more effective with a 2% first-year failure rate versus a 6% first-year rate with the diaphragm. Condoms have the additional benefit of helping to prevent the spread of some sexually transmitted infections such as HIV/AIDS, however, condoms made from animal intestine do not.

Contraceptive sponges combine a barrier with a spermicide. Like diaphragms, they are inserted vaginally before intercourse and must be placed over the cervix to be effective. Typical failure rates during the first year depend on whether or not a woman has previously given birth, being 24% in those who have and 12% in those who have not. The sponge can be inserted up to 24 hours before intercourse and must be left in place for at least six hours afterward. Allergic reactions and more severe adverse effects such as toxic shock syndrome have been reported.

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  A rolled up male condom.

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  An unrolled male latex condom

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  A polyurethane female condom

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  A diaphragm vaginal-cervical barrier, in its case with a quarter U.S. coin.

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  A contraceptive sponge set inside its open package.

Intrauterine devices

Copper T shaped IUD with removal strings

The current intrauterine devices (IUD) are small devices, often 'T'-shaped, containing either copper or levonorgestrel, which are inserted into the uterus. They are one form of long-acting reversible contraception which are the most effective types of reversible birth control. Failure rates with the copper IUD is about 0.8% while the levonorgestrel IUD has a failure rates of 0.2% in the first year of use. Among types of birth control, they, along with birth control implants, result in the greatest satisfaction among users. As of 2007, IUDs are the most widely used form of reversible contraception, with more than 180 million users worldwide.

Evidence supports effectiveness and safety in adolescents and those who have and have not previously had children. IUDs do not affect breastfeeding and can be inserted immediately after delivery. They may also be used immediately after an abortion. Once removed, even after long term use, fertility returns to normal immediately.

While copper IUDs may increase menstrual bleeding and result in more painful cramps, hormonal IUDs may reduce menstrual bleeding or stop menstruation altogether. Cramping can be treated with painkillers like non-steroidal anti-inflammatory drugs. Other potential complications include expulsion (2–5%) and rarely perforation of the uterus (less than 0.7%). A previous model of the intrauterine device (the Dalkon shield) was associated with an increased risk of pelvic inflammatory disease, however the risk is not affected with current models in those without sexually transmitted infections around the time of insertion. IUDs appear to decrease the risk of ovarian cancer.

Sterilization

Surgical sterilization is available in the form of tubal ligation for women and vasectomy for men. There are no significant long term side effects, and tubal ligation decreases the risk of ovarian cancer. Short term complications are twenty times less likely from a vasectomy than a tubal ligation. After a vasectomy, there may be swelling and pain of the scrotum which usually resolves in one or two weeks. With tubal ligation, complications occur in 1 to 2 percent of procedures with serious complications usually due to the anesthesia. Neither method offers protection from sexually transmitted infections. Sometimes, salpingectomy is also used for sterilization in women, especially for ones who are certain about not wanting children.

This decision may cause regret in some men and women. Of women who have undergone tubal ligation after the age of 30, about 6% regret their decision, as compared with 20-24% of women who received sterilization within one year of delivery and before turning 30, and 6% in nulliparous women sterilized before the age of 30. By contrast, less than 5% of men are likely to regret sterilization. Men who are more likely to regret sterilization are younger, have young or no children, or have an unstable marriage. In a survey of biological parents, 9% stated they would not have had children if they were able to do it over again.

Although sterilization is considered a permanent procedure, it is possible to attempt a tubal reversal to reconnect the fallopian tubes or a vasectomy reversal to reconnect the vasa deferentia. In women, the desire for a reversal is often associated with a change in spouse. Pregnancy success rates after tubal reversal are between 31 and 88 percent, with complications including an increased risk of ectopic pregnancy. The number of males who request reversal is between 2 and 6 percent. Rates of success in fathering another child after reversal are between 38 and 84 percent; with success being lower the longer the time period between the vasectomy and the reversal. Sperm extraction followed by in vitro fertilization may also be an option in men.

Behavioral

Behavioral methods involve regulating the timing or method of intercourse to prevent introduction of sperm into the female reproductive tract, either altogether or when an egg may be present. If used perfectly the first-year failure rate may be around 3.4%, however if used poorly first-year failure rates may approach 85%.

Fertility awareness

A CycleBeads tool, used for estimating fertility based on days since last menstruation

Fertility awareness methods involve determining the most fertile days of the menstrual cycle and avoiding unprotected intercourse. Techniques for determining fertility include monitoring basal body temperature, cervical secretions, or the day of the cycle. They have typical first-year failure rates of 24%; perfect use first-year failure rates depend on which method is used and range from 0.4% to 5%. The evidence on which these estimates are based, however, is poor as the majority of people in trials stop their use early. Globally, they are used by about 3.6% of couples. If based on both basal body temperature and another primary sign, the method is referred to as symptothermal. First-year failure rates of 20% overall and 0.4% for perfect use have been reported in clinical studies of the symptothermal method. A number of fertility tracking apps are available, as of 2016, but they are more commonly designed to assist those trying to get pregnant rather than prevent pregnancy.

Withdrawal

The withdrawal method (also known as coitus interruptus) is the practice of ending intercourse ("pulling out") before ejaculation. The main risk of the withdrawal method is that the man may not perform the maneuver correctly or in a timely manner. First-year failure rates vary from 4% with perfect usage to 22% with typical usage. It is not considered birth control by some medical professionals.

There is little data regarding the sperm content of pre-ejaculatory fluid. While some tentative research did not find sperm, one trial found sperm present in 10 out of 27 volunteers. The withdrawal method is used as birth control by about 3% of couples.

Abstinence

Sexual abstinence may be used as a form of birth control, meaning either not engaging in any type of sexual activity, or specifically not engaging in vaginal intercourse, while engaging in other forms of non-vaginal sex. Complete sexual abstinence is 100% effective in preventing pregnancy. However, among those who take a pledge to abstain from premarital sex, as many as 88% who engage in sex, do so prior to marriage. The choice to abstain from sex cannot protect against pregnancy as a result of rape, and public health efforts emphasizing abstinence to reduce unwanted pregnancy may have limited effectiveness, especially in developing countries and among disadvantaged groups.

Deliberate non-penetrative sex without vaginal sex or deliberate oral sex without vaginal sex are also sometimes considered birth control. While this generally avoids pregnancy, pregnancy can still occur with intercrural sex and other forms of penis-near-vagina sex (genital rubbing, and the penis exiting from anal intercourse) where sperm can be deposited near the entrance to the vagina and can travel along the vagina's lubricating fluids.

Abstinence-only sex education does not reduce teenage pregnancy. Teen pregnancy rates and STI rates are generally the same or higher in states where students are given abstinence-only education, as compared with comprehensive sex education. Some authorities recommend that those using abstinence as a primary method have backup methods available (such as condoms or emergency contraceptive pills).

Lactation

The lactational amenorrhea method involves the use of a woman's natural postpartum infertility which occurs after delivery and may be extended by breastfeeding. This usually requires the presence of no periods, exclusively breastfeeding the infant, and a child younger than six months. The World Health Organization states that if breastfeeding is the infant's only source of nutrition, the failure rate is 2% in the six months following delivery. Six uncontrolled studies of lactational amenorrhea method users found failure rates at 6 months postpartum between 0% and 7.5%. Failure rates increase to 4–7% at one year and 13% at two years. Feeding formula, pumping instead of nursing, the use of a pacifier, and feeding solids all increase its failure rate. In those who are exclusively breastfeeding, about 10% begin having periods before three months and 20% before six months. In those who are not breastfeeding, fertility may return four weeks after delivery.

Emergency

A split dose of two emergency contraceptive pills

Emergency contraceptive methods are medications (sometimes misleadingly referred to as "morning-after pills") or devices used after unprotected sexual intercourse with the hope of preventing pregnancy. Emergency contraceptives are often given to victims of rape. They work primarily by preventing ovulation or fertilization. They are unlikely to affect implantation, but this has not been completely excluded. A number of options exist, including high dose birth control pills, levonorgestrel, mifepristone, ulipristal and IUDs. Providing emergency contraceptive pills to women in advance does not affect rates of sexually transmitted infections, condom use, pregnancy rates, or sexual risk-taking behavior. All methods have minimal side effects.

Levonorgestrel pills, when used within 3 days, decrease the chance of pregnancy after a single episode of unprotected sex or condom failure by 70% (resulting in a pregnancy rate of 2.2%). Ulipristal, when used within 5 days, decreases the chance of pregnancy by about 85% (pregnancy rate 1.4%) and is more effective than levonorgestrel. Mifepristone is also more effective than levonorgestrel, while copper IUDs are the most effective method. IUDs can be inserted up to five days after intercourse and prevent about 99% of pregnancies after an episode of unprotected sex (pregnancy rate of 0.1 to 0.2%).This makes them the most effective form of emergency contraceptive. In those who are overweight or obese, levonorgestrel is less effective and an IUD or ulipristal is recommended.

Dual protection

Dual protection is the use of methods that prevent both sexually transmitted infections and pregnancy. This can be with condoms either alone or along with another birth control method or by the avoidance of penetrative sex.

If pregnancy is a high concern, using two methods at the same time is reasonable. For example, two forms of birth control are recommended in those taking the anti-acne drug isotretinoin or anti-epileptic drugs like carbamazepine, due to the high risk of birth defects if taken during pregnancy.

Effects

Health

Maternal mortality rate as of 2010.

 

Birth control use and total fertility rate by region.

Contraceptive use in developing countries is estimated to have decreased the number of maternal deaths by 40% (about 270,000 deaths prevented in 2008) and could prevent 70% of deaths if the full demand for birth control were met. These benefits are achieved by reducing the number of unplanned pregnancies that subsequently result in unsafe abortions and by preventing pregnancies in those at high risk.

Birth control also improves child survival in the developing world by lengthening the time between pregnancies. In this population, outcomes are worse when a mother gets pregnant within eighteen months of a previous delivery. Delaying another pregnancy after a miscarriage however does not appear to alter risk and women are advised to attempt pregnancy in this situation whenever they are ready.

Teenage pregnancies, especially among younger teens, are at greater risk of adverse outcomes including early birth, low birth weight, and death of the infant. In the United States 82% of pregnancies in those between 15 and 19 are unplanned. Comprehensive sex education and access to birth control are effective in decreasing pregnancy rates in this age group.

Finances

Map of countries by fertility rate (2020)

In the developing world, birth control increases economic growth due to there being fewer dependent children and thus more women participating in or increased contribution to the workforce. Women's earnings, assets, body mass index, and their children's schooling and body mass index all improve with greater access to birth control. Family planning, via the use of modern birth control, is one of the most cost-effective health interventions. For every dollar spent, the United Nations estimates that two to six dollars are saved. These cost savings are related to preventing unplanned pregnancies and decreasing the spread of sexually transmitted illnesses. While all methods are beneficial financially, the use of copper IUDs resulted in the greatest savings.

The total medical cost for a pregnancy, delivery and care of a newborn in the United States is on average $21,000 for a vaginal delivery and $31,000 for a caesarean delivery as of 2012. In most other countries, the cost is less than half. For a child born in 2011, an average US family will spend $235,000 over 17 years to raise them.

Prevalence

World map colored according to modern birth control use. Each shading level represents a range of six percentage points, with usage less than or equal to:
 

6%   12%   18%   24%

30%   36%   48%   60%

66%   78%   86%   No data

Demand for family planning satisfied by modern methods as of 2017.

Globally, as of 2009, approximately 60% of those who are married and able to have children use birth control. How frequently different methods are used varies widely between countries. The most common method in the developed world is condoms and oral contraceptives, while in Africa it is oral contraceptives and in Latin America and Asia it is sterilization. In the developing world overall, 35% of birth control is via female sterilization, 30% is via IUDs, 12% is via oral contraceptives, 11% is via condoms, and 4% is via male sterilization.

While less used in the developed countries than the developing world, the number of women using IUDs as of 2007 was more than 180 million. Avoiding sex when fertile is used by about 3.6% of women of childbearing age, with usage as high as 20% in areas of South America. As of 2005, 12% of couples are using a male form of birth control (either condoms or a vasectomy) with higher rates in the developed world. Usage of male forms of birth control has decreased between 1985 and 2009. Contraceptive use among women in Sub-Saharan Africa has risen from about 5% in 1991 to about 30% in 2006.

As of 2012, 57% of women of childbearing age want to avoid pregnancy (867 of 1,520 million). About 222 million women however were not able to access birth control, 53 million of whom were in sub-Saharan Africa and 97 million of whom were in Asia. This results in 54 million unplanned pregnancies and nearly 80,000 maternal deaths a year. Part of the reason that many women are without birth control is that many countries limit access due to religious or political reasons, while another contributor is poverty. Due to restrictive abortion laws in Sub-Saharan Africa, many women turn to unlicensed abortion providers for unintended pregnancy, resulting in about 2–4% obtaining unsafe abortions each year.

History

Early history

Ancient silver coin from Cyrene depicting a stalk of silphium

The Egyptian Ebers Papyrus from 1550 BC and the Kahun Papyrus from 1850 BC have within them some of the earliest documented descriptions of birth control: the use of honey, acacia leaves and lint to be placed in the vagina to block sperm. Silphium, a species of giant fennel native to north Africa, may have been used as birth control in ancient Greece and the ancient Near East. Due to its supposed desirability, by the first century AD, it had become so rare that it was worth more than its weight in silver and, by late antiquity, it was fully extinct. Most methods of birth control used in antiquity were probably ineffective.

The ancient Greek philosopher Aristotle (c. 384–322 BC) recommended applying cedar oil to the womb before intercourse, a method which was probably only effective on occasion. A Hippocratic text On the Nature of Women recommended that a woman drink a copper salt dissolved in water, which it claimed would prevent pregnancy for a year. This method was not only ineffective, but also dangerous, as the later medical writer Soranus of Ephesus (c. 98–138 AD) pointed out. Soranus attempted to list reliable methods of birth control based on rational principles. He rejected the use of superstition and amulets and instead prescribed mechanical methods such as vaginal plugs and pessaries using wool as a base covered in oils or other gummy substances. Many of Soranus's methods were probably also ineffective.

In medieval Europe, any effort to halt pregnancy was deemed immoral by the Catholic Church, although it is believed that women of the time still used a number of birth control measures, such as coitus interruptus and inserting lily root and rue into the vagina. Women in the Middle Ages were also encouraged to tie weasel testicles around their thighs during sex to prevent pregnancy. The oldest condoms discovered to date were recovered in the ruins of Dudley Castle in England, and are dated back to 1640. They were made of animal gut, and were most likely used to prevent the spread of sexually transmitted diseases during the English Civil War. Casanova, living in 18th century Italy, described the use of a lambskin covering to prevent pregnancy; however, condoms only became widely available in the 20th century.

Birth control movement

"And the villain still pursues her", a satirical Victorian era postcard

The birth control movement developed during the 19th and early 20th centuries. The Malthusian League, based on the ideas of Thomas Malthus, was established in 1877 in the United Kingdom to educate the public about the importance of family planning and to advocate for getting rid of penalties for promoting birth control. It was founded during the "Knowlton trial" of Annie Besant and Charles Bradlaugh, who were prosecuted for publishing on various methods of birth control.

In the United States, Margaret Sanger and Otto Bobsein popularized the phrase "birth control" in 1914. Sanger primarily advocated for birth control on the idea that it would prevent women from seeking unsafe abortions, but during her lifetime, she began to campaign for it on the grounds that it would reduce mental and physical defects. She was mainly active in the United States but had gained an international reputation by the 1930s. At the time, under the Comstock Law, distribution of birth control information was illegal. She jumped bail in 1914 after her arrest for distributing birth control information and left the United States for the United Kingdom. In the U.K., Sanger, influenced by Havelock Ellis, further developed her arguments for birth control. She believed women needed to enjoy sex without fearing a pregnancy. During her time abroad, Sanger also saw a more flexible diaphragm in a Dutch clinic, which she thought was a better form of contraceptive. Once Sanger returned to the United States, she established a short-lived birth-control clinic with the help of her sister, Ethel Bryne, based in the Brownville section of Brooklyn, New York in 1916. It was shut down after eleven days and resulted in her arrest. The publicity surrounding the arrest, trial, and appeal sparked birth control activism across the United States. Besides her sister, Sanger was helped in the movement by her first husband, William Sanger, who distributed copies of “Family Limitation.” Sanger's second husband, James Noah H. Slee, would also later become involved in the movement, acting as its main funder.

The increased use of birth control was seen by some as a form of social decay. A decrease of fertility was seen as a negative. Throughout the Progressive Era (1890-1920), there was an increase of voluntary associations aiding the contraceptive movement. These organizations failed to enlist more than 100,000 women because the use of birth control was often compared to eugenics; however, there were women seeking a community with like-minded women. The ideology that surrounded birth control started to gain traction during the Progressive Era due to voluntary associations establishing community. Birth control was unlike the Victorian Era because women wanted to manage their sexuality. The use of birth control was another form of self-interest women clung to. This was seen as women began to gravitate towards strong figures, like the Gibson girl.

The first permanent birth-control clinic was established in Britain in 1921 by Marie Stopes working with the Malthusian League. The clinic, run by midwives and supported by visiting doctors, offered women's birth-control advice and taught them the use of a cervical cap. Her clinic made contraception acceptable during the 1920s by presenting it in scientific terms. In 1921, Sanger founded the American Birth Control League, which later became the Planned Parenthood Federation of America. In 1924 the Society for the Provision of Birth Control Clinics was founded to campaign for municipal clinics; this led to the opening of a second clinic in Greengate, Salford in 1926. Throughout the 1920s, Stopes and other feminist pioneers, including Dora Russell and Stella Browne, played a major role in breaking down taboos about sex. In April 1930 the Birth Control Conference assembled 700 delegates and was successful in bringing birth control and abortion into the political sphere – three months later, the Ministry of Health, in the United Kingdom, allowed local authorities to give birth-control advice in welfare centres.

The National Birth Control Association was founded in Britain in 1931, and became the Family Planning Association eight years later. The Association amalgamated several British birth control-focused groups into 'a central organisation' for administering and overseeing birth control in Britain. The group incorporated the Birth Control Investigation Committee, a collective of physicians and scientists that was founded to investigate scientific and medical aspects of contraception with 'neutrality and impartiality'. Subsequently, the Association effected a series of 'pure' and 'applied' product and safety standards that manufacturers must meet to ensure their contraceptives could be prescribed as part of the Association's standard two-part-technique combining ‘a rubber appliance to protect the mouth of the womb’ with a ‘chemical preparation capable of destroying... sperm’. Between 1931 and 1959, the Association founded and funded a series of tests to assess chemical efficacy and safety and rubber quality. These tests became the basis for the Association's Approved List of contraceptives, which was launched in 1937, and went on to become an annual publication that the expanding network of FPA clinics relied upon as a means to 'establish facts [about contraceptives] and to publish these facts as a basis on which a sound public and scientific opinion can be built'.

In 1936, the United States Court of Appeals for the Second Circuit ruled in United States v. One Package of Japanese Pessaries that medically prescribing contraception to save a person's life or well-being was not illegal under the Comstock Laws. Following this decision, the American Medical Association Committee on Contraception revoked its 1936 statement condemning birth control. A national survey in 1937 showed 71 percent of the adult population supported the use of contraception. By 1938, 347 birth control clinics were running in the United States despite their advertisement still being illegal. First Lady Eleanor Roosevelt publicly supported birth control and family planning. The restrictions on birth control in the Comstock laws were effectively rendered null and void by Supreme Court decisions Griswold v. Connecticut (1965) and Eisenstadt v. Baird (1972). In 1966, President Lyndon B. Johnson started endorsing public funding for family planning services, and the Federal Government began subsidizing birth control services for low-income families. The Affordable Care Act, passed into law on March 23, 2010, under President Barack Obama, requires all plans in the Health Insurance Marketplace to cover contraceptive methods. These include barrier methods, hormonal methods, implanted devices, emergency contraceptives, and sterilization procedures.

Modern methods

In 1909, Richard Richter developed the first intrauterine device made from silkworm gut, which was further developed and marketed in Germany by Ernst Gräfenberg in the late 1920s. In 1951, an Austrian-born American chemist, named Carl Djerassi at Syntex in Mexico City made the hormones in progesterone pills using Mexican yams (Dioscorea mexicana). Djerassi had chemically created the pill but was not equipped to distribute it to patients. Meanwhile, Gregory Pincus and John Rock with help from the Planned Parenthood Federation of America developed the first birth control pills in the 1950s, such as mestranol/noretynodrel, which became publicly available in the 1960s through the Food and Drug Administration under the name Enovid. Medical abortion became an alternative to surgical abortion with the availability of prostaglandin analogs in the 1970s and mifepristone in the 1980s.

Society and culture

Legal positions

Human rights agreements require most governments to provide family planning and contraceptive information and services. These include the requirement to create a national plan for family planning services, remove laws that limit access to family planning, ensure that a wide variety of safe and effective birth control methods are available including emergency contraceptives, make sure there are appropriately trained healthcare providers and facilities at an affordable price, and create a process to review the programs implemented. If governments fail to do the above it may put them in breach of binding international treaty obligations.

In the United States, the 1965 Supreme Court decision Griswold v. Connecticut overturned a state law prohibiting dissemination of contraception information based on a constitutional right to privacy for marital relationships. In 1971, Eisenstadt v. Baird extended this right to privacy to single people.

In 2010, the United Nations launched the Every Woman Every Child movement to assess the progress toward meeting women's contraceptive needs. The initiative has set a goal of increasing the number of users of modern birth control by 120 million women in the world's 69 poorest countries by the year 2020. Additionally, they aim to eradicate discrimination against girls and young women who seek contraceptives. The American Congress of Obstetricians and Gynecologists (ACOG) recommended in 2014 that oral birth control pills should be over the counter medications.

Since at least the 1870s, American religious, medical, legislative, and legal commentators have debated contraception laws. Ana Garner and Angela Michel have found that in these discussions men often attach reproductive rights to moral and political matters, as part of an ongoing attempt to regulate human bodies. In press coverage between 1873 and 2013 they found a divide between institutional ideology and real-life experiences of women.

Religious views

Religions vary widely in their views of the ethics of birth control. The Roman Catholic Church re-affirmed its rejection of artificial contraception in 1968 and only accepts natural family planning, although large numbers of Catholics in developed countries accept and use modern methods of birth control. Among Protestants, there is a wide range of views from supporting none, such as in the Quiverfull movement, to allowing all methods of birth control. Views in Judaism range from the stricter Orthodox sect, which prohibits all methods of birth control, to the more relaxed Reform sect, which allows most. Hindus may use both natural and modern contraceptives. A common Buddhist view is that preventing conception is acceptable, while intervening after conception has occurred is not. In Islam, contraceptives are allowed if they do not threaten health, although their use is discouraged by some.

World Contraception Day

September 26 is World Contraception Day, devoted to raising awareness and improving education about sexual and reproductive health, with a vision of a world where every pregnancy is wanted. It is supported by a group of governments and international NGOs, including the Office of Population Affairs, the Asian Pacific Council on Contraception, Centro Latinamericano Salud y Mujer, the European Society of Contraception and Reproductive Health, the German Foundation for World Population, the International Federation of Pediatric and Adolescent Gynecology, International Planned Parenthood Federation, the Marie Stopes International, Population Services International, the Population Council, the United States Agency for International Development (USAID), and Women Deliver.

Misconceptions

There are a number of common misconceptions regarding sex and pregnancy. Douching after sexual intercourse is not an effective form of birth control. Additionally, it is associated with a number of health problems and thus is not recommended. Women can become pregnant the first time they have sexual intercourse and in any sexual position. It is possible, although not very likely, to become pregnant during menstruation. Contraceptive use regardless of its duration and type does not have a negative effect on the ability of women to conceive following termination of use and it doesn't significantly delay fertility. On the other hand, women who used oral contraceptives for a longer duration may had a slightly lower rate of pregnancy than did women using oral contraceptives for a shorter period of time which could be the effect of age, in which fertility decreases as age advances.

Accessibility

Access to birth control may be affected by finances and the laws within a region or country. In the United States African American, Hispanic, and young women are disproportionately affected by limited access to birth control, as a result of financial disparity. For example, Hispanic and African American women often lack insurance coverage and are more often poor. New immigrants in the United States are not offered preventive care such as birth control.

Research directions

Females

Improvements of existing birth control methods are needed, as around half of those who get pregnant unintentionally are using birth control at the time. A number of alterations of existing contraceptive methods are being studied, including a better female condom, an improved diaphragm, a patch containing only progestin, and a vaginal ring containing long-acting progesterone. This vaginal ring appears to be effective for three or four months and is currently available in some areas of the world. For women who rarely have sex, the taking of the hormonal birth control levonorgestrel around the time of sex looks promising.

A number of methods to perform sterilization via the cervix are being studied. One involves putting quinacrine in the uterus which causes scarring and infertility. While the procedure is inexpensive and does not require surgical skills, there are concerns regarding long-term side effects. Another substance, polidocanol, which functions in the same manner is being looked at. A device called Essure, which expands when placed in the fallopian tubes and blocks them, was approved in the United States in 2002. In 2016, a black boxed warning regarding potentially serious side effects was added, and in 2018, the device was discontinued.

Males

Methods of male birth control include condoms, vasectomies and withdrawal. Between 25 and 75% of males who are sexually active would use hormonal birth control if it was available for them. A number of hormonal and non-hormonal methods are in trials, and there is some research looking at the possibility of contraceptive vaccines.

A reversible surgical method under investigation is reversible inhibition of sperm under guidance (RISUG) which consists of injecting a polymer gel, styrene maleic anhydride in dimethyl sulfoxide, into the vas deferens. An injection with sodium bicarbonate washes out the substance and restores fertility. Another is an intravas device which involves putting a urethane plug into the vas deferens to block it. A combination of an androgen and a progestin seems promising, as do selective androgen receptor modulators. Ultrasound and methods to heat the testicles have undergone preliminary studies.

Other animals

Neutering or spaying, which involves removing some of the reproductive organs, is often carried out as a method of birth control in household pets. Many animal shelters require these procedures as part of adoption agreements. In large animals the surgery is known as castration.

Birth control is also being considered as an alternative to hunting as a means of controlling overpopulation in wild animals. Contraceptive vaccines have been found to be effective in a number of different animal populations. Kenyan goat herders fix a skirt, called an olor, to male goats to prevent them from impregnating female goats.