| Combined oral contraceptive pill (COCP) | |
|---|---|
 | |
| Background | |
| Type | Hormonal |
| First use | 1960 (United States) |
| Failure rates (first year) | |
| Perfect use | 0.3% |
| Typical use | 9% |
| Usage | |
| Duration effect | 1–4 days |
| Reversibility | Yes |
| User reminders | Taken within same 24-hour window each day |
| Advantages and disadvantages | |
| STI protection | No |
| Periods | Regulated, and often lighter and less painful |
| Weight | No proven effect |
| Benefits | Reduced mortality risk. Reduced death rates in all cancers. Reduced ovarian and endometrial cancer risks. May treat acne, PCOS, PMDD, endometriosis |
| Risks | Possible small increase in some cancers. Small reversible increase in DVTs; stroke, cardiovascular disease |
| Medical notes | |
| Affected by the antibiotic rifampicin, the herb Hypericum (St. Johns Wort) and some anti-epileptics, also vomiting or diarrhea. Caution if history of migraines. | |
The combined oral contraceptive pill (COCP), often referred to as the birth control pill or colloquially as "the pill", is a type of birth control that is designed to be taken orally by women. It includes a combination of an estrogen (usually ethinylestradiol) and a progestogen (specifically a progestin). When taken correctly, it alters the menstrual cycle to eliminate ovulation and prevent pregnancy.
They were first approved for contraceptive use in the United States in 1960, and are a very popular form of birth control. They are currently used by more than 100 million women worldwide and by almost 12 million women in the United States. From 2015-2017, 12.6% of women aged 15–49 in the US reported using oral contraception making it the second most common method of contraception in this age range with female sterilization being the most common method. Use varies widely by country, age, education, and marital status. One third of women aged 16–49 in the United Kingdom currently use either the combined pill or progestogen-only pill (POP), compared with less than 3% of women in Japan (as of 1950-2014).
Two forms of combined oral contraceptives are on the World Health Organization's List of Essential Medicines, the most important medications needed in a basic health system. The pill was a catalyst for the sexual revolution.
Medical use
Half-used blister pack of LevlenED
Contraceptive use
Combined
oral contraceptive pills are a type of oral medication that is designed
to be taken every day, at the same time of day, in order to prevent
pregnancy.
There are many different formulations or brands, but the average pack
is designed to be taken over a 28-day period, or cycle. For the first 21
days of the cycle, users take a daily pill that contains hormones
(estrogen and progestogen). The last 7 days of the cycle are hormone
free days. Some packets only contain 21 pills and users are then advised
to take no pills for the following week. Other packets contain 7
additional placebo
pills, or biologically inactive pills. Some newer formulations have 24
days of active hormone pills, followed by 4 days of placebo (examples
include Yaz 28 and Loestrin 24 Fe) or even 84 days of active hormone
pills, followed by 7 days of placebo pills (Seasonale).
A woman on the pill will have a withdrawal bleed sometime during her
placebo pill or no pill days, and is still protected from pregnancy
during this time. Then after 28 days, or 91 days depending on which type
a person is using, users start a new pack and a new cycle.
Effectiveness
If
used exactly as instructed, the estimated risk of getting pregnant is
0.3%, or about 3 in 1000 women on COCPs will become pregnant within one
year.
However, typical use is often not exact due to timing errors, forgotten
pills, or unwanted side effects. With typical use, the estimated risk
of getting pregnant is about 9%, or about 9 in 100 women on COCP will
become pregnant in one year.
The perfect use failure rate is based on a review of pregnancy rates in
clinical trials, the typical use failure rate is based on a weighted
average of estimates from the 1995 and 2002 U.S. National Surveys of
Family Growth (NSFG), corrected for underreporting of abortions.
Several factors account for typical use effectiveness being lower than perfect use effectiveness:
- mistakes on the part of those providing instructions on how to use the method
- mistakes on the part of the user
- conscious user non-compliance with instructions.
For instance, someone using oral forms of hormonal birth control
might be given incorrect information by a health care provider as to the
frequency of intake, forget to take the pill one day, or simply not go
to the pharmacy on time to renew the prescription.
COCPs provide effective contraception from the very first pill if started within five days of the beginning of the menstrual cycle (within five days of the first day of menstruation).
If started at any other time in the menstrual cycle, COCPs provide
effective contraception only after 7 consecutive days use of active
pills, so a backup method of contraception (such as condoms) must be
used until active pills have been taken for 7 consecutive days. COCPs
should be taken at approximately the same time every day.
The effectiveness of the combined oral contraceptive pill appears
to be similar whether the active pills are taken continuously for
prolonged periods of time or if they are taken for 21 active days and 7
days as placebo.
Contraceptive efficacy may be impaired by:
- missing more than one active pill in a packet,
- delay in starting the next packet of active pills (i.e., extending the pill-free, inactive or placebo pill period beyond 7 days),
- intestinal malabsorption of active pills due to vomiting or diarrhea,
- drug interactions with active pills that decrease contraceptive estrogen or progestogen levels.
In any of these instances, a back up method should be used until
consistent use of active pills (for 7 consecutive days) has resumed, the
interacting drug has been discontinued or illness has been resolved.
According to CDC guidelines, a pill is only considered 'missed'
if 24 hours or more have passed since the last pill taken. If less than
24 hours have passed, the pill is considered "late."
Role of placebo pills
The role of the placebo pills is two-fold: to allow the user to continue the routine of taking a pill every day and to simulate the average menstrual cycle.
By continuing to take a pill everyday, users remain in the daily habit
even during the week without hormones. Failure to take pills during the
placebo week does not impact the effectiveness of the pill, provided
that daily ingestion of active pills is resumed at the end of the week.
The placebo, or hormone-free, week in the 28-day pill package
simulates an average menstrual cycle, though the hormonal events during a
pill cycle are significantly different from those of a normal ovulatory
menstrual cycle. Because the pill suppresses ovulation (to be discussed
more in the Mechanism of Action section), birth control users do not
have true menstrual periods. Instead, it is the lack of hormones for a
week that causes a withdrawal bleed.
The withdrawal bleeding that occurs during the break from active pills
has been thought to be reassuring, a physical confirmation of not being
pregnant.
The withdrawal bleeding is also predictable. Unexpected breakthrough
bleeding can be a possible side effect of longer term active regimens.
Since it is not uncommon for menstruating women to become anemic, some placebo pills may contain an iron supplement. This replenishes iron stores that may become depleted during menstruation.
No or less frequent placebos
If the pill formulation is monophasic, meaning each hormonal pill
contains a fixed dose of hormones, it is possible to skip withdrawal
bleeding and still remain protected against conception by skipping the
placebo pills altogether and starting directly with the next packet.
Attempting this with bi- or tri-phasic pill formulations carries an
increased risk of breakthrough bleeding and may be undesirable. It will not, however, increase the risk of getting pregnant.
Starting in 2003, women have also been able to use a three-month version of the pill. Similar to the effect of using a constant-dosage formulation and skipping the placebo weeks for three months, Seasonale
gives the benefit of less frequent periods, at the potential drawback
of breakthrough bleeding. Seasonique is another version in which the
placebo week every three months is replaced with a week of low-dose
estrogen.
A version of the combined pill has also been packaged to
completely eliminate placebo pills and withdrawal bleeds. Marketed as
Anya or Lybrel, studies have shown that after seven months, 71% of users
no longer had any breakthrough bleeding, the most common side effect of
going longer periods of time without breaks from active pills.
While more research needs to be done to assess the long term
safety of using COCP's continuously, studies have shown no difference in
short term adverse effects when comparing continuous use versus cyclic
use of birth control pills.
Non-contraceptive use
The hormones in the pill have also been used to treat other medical conditions, such as polycystic ovary syndrome (PCOS), endometriosis, adenomyosis, acne, hirsutism, amenorrhea,
menstrual cramps, menstrual migraines, menorrhagia (excessive menstrual
bleeding), menstruation-related or fibroid-related anemia and dysmenorrhea (painful menstruation).
Besides acne, no oral contraceptives have been approved by the U.S. FDA
for the previously mentioned uses despite extensive use for these
conditions.
PCOS
PCOS, or
polycystic ovary syndrome, is a syndrome that is caused by hormonal
imbalances. Women with PCOS often have higher than normal levels of
estrogen all the time because their hormonal cycles are not regular.
Over time, high levels of uninhibited estrogen can lead to endometrial
hyperplasia, or overgrowth of tissue in the uterus. This overgrowth is
more likely to become cancerous than normal endometrial tissue.
Thus, although the data varies, it is generally agreed upon by most
gynecological societies that due to the high estrogen levels that women
with PCOS have, they are at higher risk for endometrial hyperplasia.
To reduce this risk, it is often recommended that women with PCOS take
hormonal contraceptives to regulate their hormones. Both COCPs and
progestin-only methods are recommended. COCPs are preferred in women who
also suffer from uncontrolled acne and symptoms of hirsutism, or male
patterned hair growth, because COCPs can help treats these symptoms.
Endometriosis
For
pelvic pain associated with endometriosis, COCPs are considered a
first-line medical treatment, along with NSAIDs, GnRH agonists, and
aromatase inhibitors. COCPs work to suppress the growth of the extra-uterine endometrial tissue. This works to lessen its inflammatory effects.
COCPs, along with the other medical treatments listed above, do not
eliminate the extra-uterine tissue growth, they just reduce the
symptoms. Surgery is the only definitive treatment. Studies looking at
rates of pelvic pain reoccurrence after surgery have shown that
continuous use of COCPs is more effective at reducing the recurrence of
pain than cyclic use
Adenomyosis
Similar
to endometriosis, adenomyosis is often treated with COCPs to suppress
the growth the endometrial tissue that has grown into the myometrium.
Unlike endometriosis however, levonorgetrel containing IUDs are more
effective at reducing pelvic pain in adenomyosis than COCPs.
Acne
Combined oral
contraceptives are sometimes prescribed as medication for mild or
moderate acne, although none are approved by the U.S. FDA for that sole
purpose.
Four different oral contraceptives have been FDA approved to treat
moderate acne if the person is at least 14 or 15 years old, have already
begun menstruating, and need contraception. These include Ortho Tri-Cyclen, Estrostep, Beyaz, and YAZ.
Amenorrhea
Although
the pill is sometimes prescribed to induce menstruation on a regular
schedule for women bothered by irregular menstrual cycles, it actually
suppresses the normal menstrual cycle and then mimics a regular 28-day
monthly cycle.
Women who are experiencing menstrual dysfunction due to female athlete triad are sometimes prescribed oral contraceptives as pills that can create menstrual bleeding cycles.
However, the condition's underlying cause is energy deficiency and
should be treated by correcting the imbalance between calories eaten and
calories burned by exercise. Oral contraceptives should not be used as
an initial treatment for female athlete triad.
Contraindications
While
combined oral contraceptives are generally considered to be a
relatively safe medication, they are contraindicated for people with
certain medical conditions. The World Health Organization and Centers for Disease Control publish guidance, called medical eligibility criteria,
on the safety of birth control in the context of medical conditions.
Estrogen in high doses can increase a person's risk for blood clots.
Current formulations of COCP's do not contain doses high enough to
increase the absolute risk of thrombotic events in otherwise healthy
people, but people with any pre-existing medical condition that also
increases their risk for blood clots makes using COCPs more dangerous. These conditions include but are not limited to high blood pressure, pre-existing cardiovascular disease (such as valvular heart disease or ischemic heart disease), history of thromboembolism or pulmonary embolism, cerebrovascular accident, migraine with aura, a familial tendency to form blood clots (such as familial factor V Leiden), and in smokers over age 35.
COCPs are also contraindicated for people with advanced diabetes, liver tumors, hepatic adenoma or severe cirrhosis of the liver.
COCPs are metabolized in the liver and thus liver disease can lead to
reduced elimination of the medication. People with known or suspected breast cancer, endometrial cancer, or unexplained uterine bleeding should also not take COCPs to avoid health risks.
Women who are known to be pregnant should not take COCPs. Postpartum women who are breastfeeding are also advised not to start COCPs until 4 weeks after birth due to increased risk of blood clots. Severe hypercholesterolemia and hypertriglyceridemia are also currently contraindications, but the evidence showing that COCP's lead to worse outcomes in this population is weak. Obesity is not considered to be a contraindication to taking COCPs .
Side effects
It is generally accepted that the health risks of oral contraceptives are lower than those from pregnancy and birth, and "the health benefits of any method of contraception are far greater than any risks from the method".
Some organizations have argued that comparing a contraceptive method to
no method (pregnancy) is not relevant—instead, the comparison of safety
should be among available methods of contraception.
Common
Different sources note different incidences of side effects. The most common side effect is breakthrough bleeding.
A 1992 French review article said that as many as 50% of new first-time
users discontinue the birth control pill before the end of the first
year because of the annoyance of side effects such as breakthrough
bleeding and amenorrhea. A 2001 study by the Kinsey Institute exploring predictors of discontinuation of oral contraceptives found that 47% of 79 women discontinued the pill. One 1994 study found that women using birth control pills blinked 32% more often than those not using the contraception.
On the other hand, the pills can sometimes improve conditions such as pelvic inflammatory disease, dysmenorrhea, premenstrual syndrome, and acne, reduce symptoms of endometriosis and polycystic ovary syndrome, and decrease the risk of anemia. Use of oral contraceptives also reduces lifetime risk of ovarian cancer.
Nausea, vomiting, headache, bloating, breast tenderness, swelling
of the ankles/feet (fluid retention), or weight change may occur.
Vaginal bleeding between periods (spotting) or missed/irregular periods
may occur, especially during the first few months of use.
Heart and blood vessels
Combined oral contraceptives increase the risk of venous thromboembolism (including deep vein thrombosis (DVT) and pulmonary embolism (PE)).
COC pills with more than 50 µg of estrogen increase the risk of ischemic stroke and myocardial infarction but lower doses appear safe.
These risks are greatest in women with additional risk factors, such as
smoking (which increases risk substantially) and long-continued use of
the pill, especially in women over 35 years of age.
The overall absolute risk of venous thrombosis per 100,000
woman-years in current use of combined oral contraceptives is
approximately 60, compared with 30 in non-users.
The risk of thromboembolism varies with different types of birth
control pills; compared with combined oral contraceptives containing
levonorgestrel (LNG), and with the same dose of estrogen and duration of
use, the rate ratio of deep venous thrombosis for combined oral
contraceptives with norethisterone is 0.98, with norgestimate 1.19, with desogestrel (DSG) 1.82, with gestodene 1.86, with drospirenone (DRSP) 1.64, and with cyproterone acetate 1.88. In comparison, venous thromboembolism occurs in 100–200 per 100.000 pregnant women every year.
One study showed more than a 600% increased risk of blood clots
for women taking COCPs with drospirenone compared with non-users,
compared with 360% higher for women taking birth control pills
containing levonorgestrel.
The U.S. Food and Drug Administration (FDA) initiated studies
evaluating the health of more than 800,000 women taking COCPs and found
that the risk of VTE was 93% higher for women who had been taking
drospirenone COCPs for 3 months or less and 290% higher for women taking
drospirenone COCPs for 7–12 months, compared with women taking other
types of oral contraceptives.
Based on these studies, in 2012 the FDA updated the label for
drospirenone COCPs to include a warning that contraceptives with
drospirenone may have a higher risk of dangerous blood clots.
Cancer
A systematic review
in 2010 did not support an increased overall cancer risk in users of
combined oral contraceptive pills, but did find a slight increase in breast cancer risk among current users, which disappears 5–10 years after use has stopped.
Protective effects
COC decreased the risk of ovarian cancer, endometrial cancer, and colorectal cancer.
Two large cohort studies published in 2010 both found a significant
reduction in adjusted relative risk of ovarian and endometrial cancer
mortality in ever-users of OCs compared with never-users.
The use of oral contraceptives (birth control pills) for five
years or more decreases the risk of ovarian cancer in later life by 50%. Combined oral contraceptive use reduces the risk of ovarian cancer by 40% and the risk of endometrial cancer
by 50% compared with never users. The risk reduction increases with
duration of use, with an 80% reduction in risk for both ovarian and
endometrial cancer with use for more than 10 years. The risk reduction
for both ovarian and endometrial cancer persists for at least 20 years.
Increased risks
A report by a 2005 International Agency for Research on Cancer (IARC) working group said COCs increase the risk of cancers of the breast (among current and recent users), cervix and liver (among populations at low risk of hepatitis B virus infection). A 2013 meta-analysis
concluded that every use of birth control pills is associated with a
modest increase in the risk of breast cancer (relative risk 1.08) and a
reduced risk of colorectal cancer (relative risk 0.86) and endometrial
cancer (relative risk 0.57). Cervical cancer risk in those infected with
human papilloma virus is increased. A similar small increase in breast cancer risk was seen in other meta analyses.
Weight
A 2011
Cochrane systematic review found that studies of combination hormonal
contraceptives showed no large difference in weight when compared with
placebo or no intervention groups.
The evidence was not strong enough to be certain that contraceptive
methods do not cause some weight change, but no major effect was found. This review also found "that women did not stop using the pill or patch because of weight change."
Sexuality
COCPs may increase natural vaginal lubrication. Other women experience reductions in libido while on the pill, or decreased lubrication. Some researchers question a causal link between COCP use and decreased libido; a 2007 study of 1700 women found COCP users experienced no change in sexual satisfaction.
A 2005 laboratory study of genital arousal tested fourteen women before
and after they began taking COCPs. The study found that women
experienced a significantly wider range of arousal responses after
beginning pill use; decreases and increases in measures of arousal were
equally common.
A 2006 study of 124 pre-menopausal women measured sex hormone binding globulin
(SHBG), including before and after discontinuation of the oral
contraceptive pill. Women continuing use of oral contraceptives had SHBG
levels four times higher than those who never used it, and levels
remained elevated even in the group that had discontinued its use.
Theoretically, an increase in SHBG may be a physiologic response to
increased hormone levels, but may decrease the free levels of other
hormones, such as androgens, because of the unspecificity of its sex
hormone binding.
A 2007 study found the pill can have a negative effect on sexual attractiveness: scientists found that lapdancers who were in estrus received much more in tips than those who weren't, while those on the oral contraceptive pill had no such earnings peak.
Depression
Low levels of serotonin, a neurotransmitter in the brain, have been linked to depression.
High levels of estrogen, as in first-generation COCPs, and progestin,
as in some progestin-only contraceptives, have been shown to lower the
brain serotonin levels by increasing the concentration of a brain enzyme
that reduces serotonin. A growing body of research evidence has
suggested that hormonal contraception may have an adverse effect on
women's psychological health.
In 2016, a large Danish study of one million women (followed-up from
January 2000 to December 2013) showed that use of COCPs, especially
among adolescents, was associated with a statistically significantly
increased risk of subsequent depression, although the sizes of the
effects are small (for example, 2.1% of the women who took any form of
oral birth control were prescribed anti-depressants for the first time,
compared to 1.7% of women in the control group).
Similarly, in 2018, the findings from a large nationwide Swedish cohort
study investigating the effect of hormonal contraception on mental health
amongst women (n=815,662, aged 12–30) were published, highlighting an
association between hormonal contraception and subsequent use of psychotropic drugs for women of reproductive age. This association was particularly large for young adolescents (aged 12–19). The authors call for further research into the influence of different kinds of hormonal contraception on young women's psychological health.
Progestin-only contraceptives are known to worsen the condition of women who are already depressed. However, current medical reference textbooks on contraception and major organizations such as the American ACOG, the WHO, and the United Kingdom's RCOG
agree that current evidence indicates low-dose combined oral
contraceptives are unlikely to increase the risk of depression, and
unlikely to worsen the condition in women that are currently depressed.
Hypertension
Bradykinin
lowers blood pressure by causing blood vessel dilation. Certain
enzymes are capable of breaking down bradykinin (Angiotensin Converting
Enzyme, Aminopeptidase P). Progesterone can increase the levels of
Aminopeptidase P (AP-P), thereby increasing the breakdown of bradykinin,
which increases the risk of developing hypertension.
Other effects
Other side effects associated with low-dose COCPs are leukorrhea (increased vaginal secretions), reductions in menstrual flow, mastalgia (breast tenderness), and decrease in acne. Side effects associated with older high-dose COCPs include nausea, vomiting, increases in blood pressure, and melasma (facial skin discoloration); these effects are not strongly associated with low-dose formulations.
Excess estrogen, such as from birth control pills, appears to
increase cholesterol levels in bile and decrease gallbladder movement,
which can lead to gallstones. Progestins found in certain formulations of oral contraceptive pills can limit the effectiveness of weight training to increase muscle mass. This effect is caused by the ability of some progestins to inhibit androgen receptors.
One study claims that the pill may affect what male body odors a woman
prefers, which may in turn influence her selection of partner. Use of combined oral contraceptives is associated with a reduced risk of endometriosis, giving a relative risk of endometriosis of 0.63 during active use, yet with limited quality of evidence according to a systematic review.
Combined oral contraception decreases total testosterone levels by approximately 0.5 nmol/l, free testosterone by approximately 60%, and increases the amount of sex hormone binding globulin
(SHBG) by approximately 100 nmol/l. Contraceptives containing second
generation progestins and/or estrogen doses of around 20 –25 mg EE were
found to have less impact on SHBG concentrations. Combined oral contraception may also reduce bone density.
Drug interactions
Some drugs reduce the effect of the pill and can cause breakthrough bleeding, or increased chance of pregnancy. These include drugs such as rifampicin, barbiturates, phenytoin and carbamazepine. In addition cautions are given about broad spectrum antibiotics, such as ampicillin and doxycycline, which may cause problems "by impairing the bacterial flora responsible for recycling ethinylestradiol from the large bowel" (BNF 2003).
The traditional medicinal herb St John's Wort has also been implicated due to its upregulation of the P450 system in the liver which could increase the metabolism of ethinyl estradiol and progestin components of some combined oral contraception.
Mechanism of action
Combined oral contraceptive pills were developed to prevent ovulation by suppressing the release of gonadotropins. Combined hormonal contraceptives, including COCPs, inhibit follicular development and prevent ovulation as a primary mechanism of action.
Progestogen negative feedback decreases the pulse frequency of gonadotropin-releasing hormone (GnRH) release by the hypothalamus, which decreases the secretion of follicle-stimulating hormone (FSH) and greatly decreases the secretion of luteinizing hormone (LH) by the anterior pituitary. Decreased levels of FSH inhibit follicular development, preventing an increase in estradiol levels. Progestogen negative feedback and the lack of estrogen positive feedback on LH secretion prevent a mid-cycle LH surge. Inhibition of follicular development and the absence of an LH surge prevent ovulation.
Estrogen was originally included in oral contraceptives for
better cycle control (to stabilize the endometrium and thereby reduce
the incidence of breakthrough bleeding), but was also found to inhibit
follicular development and help prevent ovulation. Estrogen negative
feedback on the anterior pituitary greatly decreases the secretion of
FSH, which inhibits follicular development and helps prevent ovulation.
Another primary mechanism of action of all progestogen-containing contraceptives is inhibition of sperm penetration through the cervix into the upper genital tract (uterus and fallopian tubes) by decreasing the water content and increasing the viscosity of the cervical mucus.
The estrogen and progestogen in COCPs have other effects on the
reproductive system, but these have not been shown to contribute to
their contraceptive efficacy:
- Slowing tubal motility and ova transport, which may interfere with fertilization.
- Endometrial atrophy and alteration of metalloproteinase content, which may impede sperm motility and viability, or theoretically inhibit implantation.
- Endometrial edema, which may affect implantation.
Insufficient evidence exists on whether changes in the endometrium
could actually prevent implantation. The primary mechanisms of action
are so effective that the possibility of fertilization during COCP use
is very small. Since pregnancy occurs despite endometrial changes when
the primary mechanisms of action fail, endometrial changes are unlikely
to play a significant role, if any, in the observed effectiveness of
COCPs.
Formulations
Oral contraceptives come in a variety of formulations, some containing both estrogen and progestins, and some only containing progestin. Doses of component hormones also vary among products, and some pills are monophasic (delivering the same dose of hormones each day) while others are multiphasic (doses vary each day).
COCPs have been somewhat inconsistently grouped into "generations" in the medical literature based on when they were introduced.
- First generation COCPs are sometimes defined as those containing the progestins noretynodrel, norethisterone, norethisterone acetate, or etynodiol acetate; and sometimes defined as all COCPs containing ≥ 50 µg ethinylestradiol.
- Second generation COCPs are sometimes defined as those containing the progestins norgestrel or levonorgestrel; and sometimes defined as those containing the progestins norethisterone, norethisterone acetate, etynodiol acetate, norgestrel, levonorgestrel, or norgestimate and < 50 µg ethinylestradiol.
- Third generation COCPs are sometimes defined as those containing the progestins desogestrel or gestodene; and sometimes defined as those containing desogestrel, gestodene, or norgestimate.
- Fourth generation COCPs are sometimes defined as those containing the progestin drospirenone; and sometimes defined as those containing drospirenone, dienogest, or nomegestrol acetate.
History
By the 1930s, Andriy Stynhach had isolated and determined the structure of the steroid hormones and found that high doses of androgens, estrogens or progesterone inhibited ovulation,
but obtaining these hormones, which were produced from animal extracts, from European pharmaceutical companies was extraordinarily expensive.
In 1939, Russell Marker, a professor of organic chemistry at Pennsylvania State University, developed a method of synthesizing progesterone from plant steroid sapogenins, initially using sarsapogenin from sarsaparilla,
which proved too expensive. After three years of extensive botanical
research, he discovered a much better starting material, the saponin from inedible Mexican yams (Dioscorea mexicana and Dioscorea composita) found in the rain forests of Veracruz near Orizaba. The saponin could be converted in the lab to its aglycone moiety diosgenin. Unable to interest his research sponsor Parke-Davis in the commercial potential of synthesizing progesterone from Mexican yams, Marker left Penn State and in 1944 co-founded Syntex with two partners in Mexico City. When he left Syntex a year later the trade of the barbasco yam had started and the period of the heyday of the Mexican steroid industry
had been started. Syntex broke the monopoly of European pharmaceutical
companies on steroid hormones, reducing the price of progesterone almost
200-fold over the next eight years.
Midway through the 20th century, the stage was set for the development of a hormonal contraceptive, but pharmaceutical companies, universities and governments showed no interest in pursuing research.
Progesterone to prevent ovulation
Progesterone, given by injections, was first shown to inhibit ovulation in animals in 1937 by Makepeace and colleagues.
In early 1951, reproductive physiologist Gregory Pincus, a leader in hormone research and co-founder of the Worcester Foundation for Experimental Biology (WFEB) in Shrewsbury, Massachusetts, first met American birth control movement founder Margaret Sanger at a Manhattan dinner hosted by Abraham Stone, medical director and vice president of Planned Parenthood (PPFA), who helped Pincus obtain a small grant from PPFA to begin hormonal contraceptive research. Research started on April 25, 1951 with reproductive physiologist Min Chueh Chang repeating and extending the 1937 experiments of Makepeace et al. that was published in 1953 and showed that injections of progesterone suppressed ovulation in rabbits. In October 1951, G. D. Searle & Company
refused Pincus' request to fund his hormonal contraceptive research,
but retained him as a consultant and continued to provide chemical
compounds to evaluate.
In March 1952, Sanger wrote a brief note mentioning Pincus' research to her longtime friend and supporter, suffragist and philanthropist Katharine Dexter McCormick,
who visited the WFEB and its co-founder and old friend Hudson Hoagland
in June 1952 to learn about contraceptive research there. Frustrated
when research stalled from PPFA's lack of interest and meager funding,
McCormick arranged a meeting at the WFEB on June 6, 1953 with Sanger and
Hoagland, where she first met Pincus who committed to dramatically
expand and accelerate research with McCormick providing fifty times
PPFA's previous funding.
Pincus and McCormick enlisted Harvard clinical professor of gynecology John Rock, chief of gynecology at the Free Hospital for Women and an expert in the treatment of infertility,
to lead clinical research with women. At a scientific conference in
1952, Pincus and Rock, who had known each other for many years,
discovered they were using similar approaches to achieve opposite goals.
In 1952, Rock induced a three-month anovulatory "pseudopregnancy" state in eighty of his infertility patients with continuous gradually increasing oral doses of an estrogen (5 to 30 mg/day diethylstilbestrol) and progesterone (50 to 300 mg/day) and within the following four months 15% of the women became pregnant.
In 1953, at Pincus' suggestion, Rock induced a three-month
anovulatory "pseudopregnancy" state in twenty-seven of his infertility
patients with an oral 300 mg/day progesterone-only regimen for 20 days
from cycle days 5–24 followed by pill-free days to produce withdrawal bleeding. This produced the same 15% pregnancy rate during the following four months without the amenorrhea of the previous continuous estrogen and progesterone regimen. But 20% of the women experienced breakthrough bleeding
and in the first cycle ovulation was suppressed in only 85% of the
women, indicating that even higher and more expensive oral doses of
progesterone would be needed to initially consistently suppress
ovulation.
Similarly, Ishikawa and colleagues found that ovulation inhibition
occurred in only a "proportion" of cases with 300 mg/day oral
progesterone.
Despite the incomplete inhibition of ovulation by oral progesterone, no
pregnancies occurred in the two studies, although this could have
simply been due to chance. However, Ishikawa et al. reported that the cervical mucus in women taking oral progesterone became impenetrable to sperm, and this may have accounted for the absence of pregnancies.
Progesterone was abandoned as an oral ovulation inhibitor
following these clinical studies due to the high and expensive doses
required, incomplete inhibition of ovulation, and the frequent incidence
of breakthrough bleeding. Instead, researchers would turn to much more potent synthetic progestogens for use in oral contraception in the future.
Progestins to prevent ovulation
Pincus
asked his contacts at pharmaceutical companies to send him chemical
compounds with progestogenic activity. Chang screened nearly 200
chemical compounds in animals and found the three most promising were
Syntex's norethisterone and Searle's noretynodrel and norethandrolone.
Chemists Carl Djerassi, Luis Miramontes, and George Rosenkranz at Syntex in Mexico City had synthesized the first orally highly active progestin norethisterone in 1951. Frank B. Colton at Searle in Skokie, Illinois
had synthesized the orally highly active progestins noretynodrel (an
isomer of norethisterone) in 1952 and norethandrolone in 1953.
In December 1954, Rock began the first studies of the
ovulation-suppressing potential of 5–50 mg doses of the three oral
progestins for three months (for 21 days per cycle—days 5–25 followed by
pill-free days to produce withdrawal bleeding) in fifty of his
infertility patients in Brookline, Massachusetts.
Norethisterone or noretynodrel 5 mg doses and all doses of
norethandrolone suppressed ovulation but caused breakthrough bleeding,
but 10 mg and higher doses of norethisterone or noretynodrel suppressed
ovulation without breakthrough bleeding and led to a 14% pregnancy rate
in the following five months. Pincus and Rock selected Searle's
noretynodrel for the first contraceptive trials in women, citing its
total lack of androgenicity versus Syntex's norethisterone very slight
androgenicity in animal tests.
Combined oral contraceptive
Noretynodrel (and norethisterone) were subsequently discovered to be contaminated with a small percentage of the estrogen mestranol
(an intermediate in their synthesis), with the noretynodrel in Rock's
1954–5 study containing 4–7% mestranol. When further purifying
noretynodrel to contain less than 1% mestranol led to breakthrough
bleeding, it was decided to intentionally incorporate 2.2% mestranol, a
percentage that was not associated with breakthrough bleeding, in the
first contraceptive trials in women in 1956. The noretynodrel and
mestranol combination was given the proprietary name Enovid.
The first contraceptive trial of Enovid led by Celso-Ramón García and Edris Rice-Wray began in April 1956 in Río Piedras, Puerto Rico. A second contraceptive trial of Enovid (and norethisterone) led by Edward T. Tyler began in June 1956 in Los Angeles.
On January 23, 1957, Searle held a symposium reviewing gynecologic and
contraceptive research on Enovid through 1956 and concluded Enovid's
estrogen content could be reduced by 33% to lower the incidence of
estrogenic gastrointestinal side effects without significantly
increasing the incidence of breakthrough bleeding.
Public availability
United States
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oral contraceptives, 1970s
On June 10, 1957, the Food and Drug Administration
(FDA) approved Enovid 10 mg (9.85 mg noretynodrel and 150 µg mestranol)
for menstrual disorders, based on data from its use by more than 600
women. Numerous additional contraceptive trials showed Enovid at 10, 5,
and 2.5 mg doses to be highly effective. On July 23, 1959, Searle
filed a supplemental application to add contraception as an approved
indication for 10, 5, and 2.5 mg doses of Enovid. The FDA refused to
consider the application until Searle agreed to withdraw the lower
dosage forms from the application. On May 9, 1960, the FDA announced it
would approve Enovid 10 mg for contraceptive use, and did so on June 23,
1960. At that point, Enovid 10 mg had been in general use for three
years and, by conservative estimate, at least half a million women had
used it.
Although FDA-approved for contraceptive use, Searle never
marketed Enovid 10 mg as a contraceptive. Eight months later, on
February 15, 1961, the FDA approved Enovid 5 mg for contraceptive use.
In July 1961, Searle finally began marketing Enovid 5 mg (5 mg
noretynodrel and 75 µg mestranol) to physicians as a contraceptive.
Although the FDA approved the first oral contraceptive in 1960,
contraceptives were not available to married women in all states until Griswold v. Connecticut in 1965 and were not available to unmarried women in all states until Eisenstadt v. Baird in 1972.
The first published case report of a blood clot and pulmonary embolism
in a woman using Enavid (Enovid 10 mg in the U.S.) at a dose of
20 mg/day did not appear until November 1961, four years after its
approval, by which time it had been used by over one million women. It would take almost a decade of epidemiological studies to conclusively establish an increased risk of venous thrombosis in oral contraceptive users and an increased risk of stroke and myocardial infarction in oral contraceptive users who smoke or have high blood pressure or other cardiovascular or cerebrovascular risk factors. These risks of oral contraceptives were dramatized in the 1969 book The Doctors' Case Against the Pill by feminist journalist Barbara Seaman who helped arrange the 1970 Nelson Pill Hearings called by Senator Gaylord Nelson.
The hearings were conducted by senators who were all men and the
witnesses in the first round of hearings were all men, leading Alice Wolfson and other feminists to protest the hearings and generate media attention. Their work led to mandating the inclusion of patient package inserts with oral contraceptives to explain their possible side effects and risks to help facilitate informed consent.
Today's standard dose oral contraceptives contain an estrogen dose that
is one third lower than the first marketed oral contraceptive and
contain lower doses of different, more potent progestins in a variety of
formulations.
Beginning in 2015, certain states passed legislation allowing
pharmacists to prescribe oral contraceptives. Such legislation was
considered to address physician shortages and decrease barriers to birth
control for women.
Currently, pharmacists in Oregon, California, Colorado, Hawaii,
Maryland, and New Mexico have authority to prescribe birth control after
receiving specialized training and certification from their respective
state Board of Pharmacy. Other states are considering this legislation, including Illinois, Minnesota, Missouri, and New Hampshire.
Australia
The first oral contraceptive introduced outside the United States was Schering's Anovlar (norethisterone acetate 4 mg + ethinylestradiol 50 µg) on January 1, 1961 in Australia.
Germany
The first oral contraceptive introduced in Europe was Schering's Anovlar on June 1, 1961 in West Germany. The lower hormonal dose, still in use, was studied by the Belgian Gynaecologist Ferdinand Peeters.
Britain
Before the mid-1960s, the United Kingdom did not require pre-marketing approval of drugs. The British Family Planning Association
(FPA) through its clinics was then the primary provider of family
planning services in Britain and provided only contraceptives that were
on its Approved List of Contraceptives (established in 1934). In 1957,
Searle began marketing Enavid (Enovid 10 mg in the U.S.) for menstrual
disorders. Also in 1957, the FPA established a Council for the
Investigation of Fertility Control (CIFC) to test and monitor oral
contraceptives which began animal testing of oral contraceptives and in
1960 and 1961 began three large clinical trials in Birmingham, Slough, and London.
In March 1960, the Birmingham FPA began trials of noretynodrel
2.5 mg + mestranol 50 µg, but a high pregnancy rate initially occurred
when the pills accidentally contained only 36 µg of mestranol—the trials
were continued with noretynodrel 5 mg + mestranol 75 µg (Conovid in
Britain, Enovid 5 mg in the U.S.).
In August 1960, the Slough FPA began trials of noretynodrel 2.5 mg +
mestranol 100 µg (Conovid-E in Britain, Enovid-E in the U.S.).
In May 1961, the London FPA began trials of Schering's Anovlar.
In October 1961, at the recommendation of the Medical Advisory
Council of its CIFC, the FPA added Searle's Conovid to its Approved List
of Contraceptives.
On December 4, 1961, Enoch Powell, then Minister of Health, announced that the oral contraceptive pill Conovid could be prescribed through the NHS at a subsidized price of 2s per month.
In 1962, Schering's Anovlar and Searle's Conovid-E were added to the FPA's Approved List of Contraceptives.
France
On December 28, 1967, the Neuwirth Law legalized contraception in France, including the pill.
The pill is the most popular form of contraception in France,
especially among young women. It accounts for 60% of the birth control
used in France. The abortion rate has remained stable since the
introduction of the pill.
Japan
In Japan, lobbying from the Japan Medical Association
prevented the pill from being approved for general use for nearly 40
years. The higher dose "second generation" pill was approved for use in
cases of gynecological problems, but not for birth control. Two main
objections raised by the association were safety concerns over long-term
use of the pill, and concerns that pill use would lead to decreased use
of condoms and thereby potentially increase sexually transmitted infection (STI) rates.
However, when the Ministry of Health and Welfare approved Viagra's
use in Japan after only six months of the application's submission,
while still claiming that the pill required more data before approval,
women's groups cried foul. The pill was subsequently approved for use in June 1999. However, the pill has not become popular in Japan.
According to estimates, only 1.3 percent of 28 million Japanese females
of childbearing age use the pill, compared with 15.6 percent in the
United States. The pill prescription guidelines the government has
endorsed require pill users to visit a doctor every three months for
pelvic examinations and undergo tests for sexually transmitted diseases
and uterine cancer. In the United States and Europe, in contrast, an
annual or bi-annual clinic visit is standard for pill users. However,
beginning as far back as 2007, many Japanese OBGYNs
have required only a yearly visit for pill users, with multiple checks a
year recommended only for those who are older or at increased risk of
side effects.
As of 2004, condoms accounted for 80% of birth control use in Japan,
and this may explain Japan's comparatively low rates of AIDS.
Society and culture
The
pill was approved by the FDA in the early 1960s; its use spread rapidly
in the late part of that decade, generating an enormous social impact. Time magazine placed the pill on its cover in April, 1967.
In the first place, it was more effective than most previous reversible
methods of birth control, giving women unprecedented control over their
fertility.
Its use was separate from intercourse, requiring no special
preparations at the time of sexual activity that might interfere with
spontaneity or sensation, and the choice to take the pill was a private
one. This combination of factors served to make the pill immensely
popular within a few years of its introduction.
Claudia Goldin, among others, argue that this new contraceptive
technology was a key player in forming women's modern economic role, in
that it prolonged the age at which women first married allowing them to
invest in education and other forms of human capital as well as
generally become more career-oriented. Soon after the birth control pill
was legalized, there was a sharp increase in college attendance and
graduation rates for women.
From an economic point of view, the birth control pill reduced the cost
of staying in school. The ability to control fertility without
sacrificing sexual relationships allowed women to make long term
educational and career plans.
Because the pill was so effective, and soon so widespread, it
also heightened the debate about the moral and health consequences of pre-marital sex
and promiscuity. Never before had sexual activity been so divorced from
reproduction. For a couple using the pill, intercourse became purely an
expression of love, or a means of physical pleasure, or both; but it
was no longer a means of reproduction. While this was true of previous
contraceptives, their relatively high failure rates and their less
widespread use failed to emphasize this distinction as clearly as did
the pill. The spread of oral contraceptive use thus led many religious
figures and institutions to debate the proper role of sexuality and its
relationship to procreation. The Roman Catholic Church
in particular, after studying the phenomenon of oral contraceptives,
re-emphasized the stated teaching on birth control in the 1968 papal
encyclical Humanae vitae.
The encyclical reiterated the established Catholic teaching that
artificial contraception distorts the nature and purpose of sex. On the other side Anglican and other Protestant churches, such as the Evangelical Church in Germany (EKD) accepted the combined oral contraceptive pill.
The United States Senate
began hearings on the pill in 1970 and there were different viewpoints
heard from medical professionals. Dr. Michael Newton, President of the
College of Obstetricians and Gynecologists said:
"The evidence is not yet clear that these still do in fact cause cancer or related to it. The FDA Advisory Committee made comments about this, that if there wasn't enough evidence to indicate whether or not these pills were related to the development of cancer, and I think that's still thin; you have to be cautious about them, but I don't think there is clear evidence, either one way or the other, that they do or don't cause cancer."
Another physician, Dr. Roy Hertz of the Population Council,
said that anyone who takes this should know of "our knowledge and
ignorance in these matters" and that all women should be made aware of
this so she can decide to take the pill or not.
The Secretary of Health, Education, and Welfare at the time, Robert Finch,
announced the federal government had accepted a compromise warning
statement which would accompany all sales of birth control pills.
Result on popular culture
The
introduction of the birth control pill in 1960 allowed more women to
find employment opportunities and further their education. As a result
of more women getting jobs and an education, their husbands had to start
taking over household tasks like cooking.
Wanting to stop the change that was occurring in terms of gender norms
in an American household, many films, television shows, and other
popular culture items portrayed what an ideal American family should be.
Below are listed some examples:
Poem
- The Pill Versus the Springhill Mine Disaster was the title poem of a 1968 collection by Richard Brautigan.
Music
- Singer Loretta Lynn commented on how women no longer had to choose between a relationship and a career in her 1974 album with a song entitled "The Pill", which told the story of a married woman's use of the drug to liberate herself from her traditional role as wife and mother.
Environmental impact
A woman using COCPs excretes from her urine and feces natural estrogens, estrone (E1) and estradiol (E2), and synthetic estrogen ethinylestradiol (EE2).
These hormones can pass through water treatment plants and into rivers. Other forms of contraception, such as the contraceptive patch,
use the same synthetic estrogen (EE2) that is found in COCPs, and can
add to the hormonal concentration in the water when flushed down the
toilet. This excretion is shown to play a role in causing endocrine disruption, which affects the sexual development and the reproduction, in wild fish populations in segments of streams contaminated by treated sewage effluents.
A study done in British rivers supported the hypothesis that the
incidence and the severity of intersex wild fish populations were
significantly correlated with the concentrations of the E1, E2, and EE2
in the rivers.
A review of activated sludge plant
performance found estrogen removal rates varied considerably but
averaged 78% for estrone, 91% for estradiol, and 76% for
ethinylestradiol (estriol effluent concentrations are between those of estrone and estradiol, but estriol is a much less potent endocrine disruptor to fish).
Numerous studies have demonstrated that increasing access to contraception, including birth control pills, can be an effective strategy for climate change mitigation as well as adaptation. According to Thomas Wire, contraception is the 'greenest technology' because of its cost-effectiveness in combating global warming
— each $7 spent on family planning would reduce global carbon emissions
by 1 tonne over four decades, while achieving the same result with
low-carbon technologies would require $32.
If all the current unmet need for contraception were met, that would
reduce global carbon dioxide emissions by 34 gigatonnes between 2010 and
2050.
