Emergency contraception (EC), or emergency postcoital contraception, refers to contraceptive measures that, if taken after sex, may prevent pregnancy.
Forms of EC include:
As its name implies, EC is intended for occasional use, when primary means of contraception fail. Since EC methods act before implantation, they are medically and legally considered forms of contraception. Some scientists believe that EC may possibly act after fertilization (see Mechanism of action). Some religious conservatives consider EC to be an abortifacient.
The phrase "morning-after pill" is figurative; ECPs are licensed for use up to 72 hours after sexual intercourse.
The drug mifepristone may be used either as an ECP or as an abortifacient, depending on whether it is used before or after implantation. In the USA, it is most commonly used in 200- or 600-mg doses as an abortifacient, but in China it is commonly used as emergency contraception. As EC, a low dose of mifepristone is slightly less effective than higher doses, but has fewer side effects. As of 2000, the smallest dose available in the USA was 200 mg. Mifepristone, however, is not approved for emergency contraceptive use in the United States. A review of studies in humans concluded that the contraceptive effects of the 10-mg dose are due to its effects on ovulation, but understanding of its mechanism of action remains incomplete. Higher doses of mifepristone can disrupt implantation and, unlike levonorgestrel, mifepristone is effective in terminating established pregnancies.
Morning-after pills (ECPs) are not to be confused with the “abortion pill”, otherwise known as RU486, mifestone, or Mifeprex. According to the International Federation of Gynecology and Obstetrics, “EC is not an abortifacient because it has its effect prior to the earliest time of implantation.” Since they act before implantation, they are considered medically and legally to be forms of contraception.
... these numbers do not translate into a pregnancy rate of 25 percent. Rather, they mean that if 1,000 women have unprotected intercourse in the middle two weeks of their menstrual cycles, approximately 80 will become pregnant. Use of emergency contraceptive pills would reduce this number by 75 percent, to 20 women.
The progestin-only regimen (using levonorgestrel) is reported by the U.S. FDA to have an 89% effectiveness. As of 2006, the labeling on the U.S. brand Plan B explained this effectiveness rate by stating, "Seven out of every eight women who would have gotten pregnant will not become pregnant."
In 1999, a meta-analysis of eight studies of the combined (Yuzpe) regimen concluded that the best point estimate of effectiveness was 74%. A 2003 analysis of two of the largest combined (Yuzpe) regimen studies, using a different calculation method, found effectiveness estimates of 47% and 53%.
For both the progestin-only and Yuzpe regimens, the effectiveness of emergency contraception is highest when taken within 12 hours of intercourse and declines over time. While most studies of emergency contraception have only enrolled women within 72 hours of unprotected intercourse, a 2002 study by the World Health Organization (WHO) suggested that reasonable effectiveness may continue for up to 120 hours (5 days) after intercourse.
For 10 mg of mifepristone taken up to 120 hours (5 days) after intercourse, the combined estimate from three trials was an effectiveness of 83%. A review found that many trials found a regimen of 25-50 mg of mifepristone to have higher effectiveness. However, when reviewers looked at only high-quality trials, the difference in effectiveness was not statistically significant.
Placebo-controlled trials that could give a precise measure of the pregnancy rate without treatment would be unethical, so the effectiveness percentage is based on estimated pregnancy rates. This is currently done using variants of the calendar method. Women with irregular cycles for any reason (including recent hormone use such as oral contraceptives and breastfeeding) must be excluded from such calculations. Even for women included in the calculation, the limitations of calendar methods of fertility determination have long been recognized. In their April 2007 emergency review article, Trussell and Raymond note:
Calculation of effectiveness, and particularly the denominator of the fraction, involves many assumptions that are difficult to validate. Therefore, reported figures on the efficacy of emergency contraception may be underestimates or, more probably, overestimates. Yet, precise estimates of efficacy may not be highly relevant to many women who have had unprotected intercourse, since ECPs are often the only available treatment.
Recently, hormonal assay has been suggested as a more accurate method of estimating fertility for EC studies.
The WHO Medical Eligibility Criteria for Contraceptive Use list no medical condition for which the risks of emergency contraceptive pills (using progestin-only or combined oral contraceptive pills) outweigh the benefits, specifically noting breastfeeding and history of ectopic pregnancy as conditions where there are no restrictions on use of ECPs, and history of severe cardiovascular disease (heart attack, stroke, blood clots), angina, migraine, and severe liver disease (including jaundice) as conditions where the advantages of using emergency contraceptive pills generally outweigh the theoretical or proven risks. The American Academy of Pediatrics (AAP) and experts on emergency contraception say progestin-only ECPs may be preferable to combined ECPs containing estrogen in women with a history of blood clots, stroke, or migraine.
The AAP, American College of Obstetricians and Gynecologists (ACOG), U.S. Food and Drug Administration, the WHO, the Royal College of Obstetricians and Gynaecologists's Faculty of Family Planning & Reproductive Health Care (FFPRHC) and other experts on emergency contraception state that there are no medical conditions in which progestin-only ECPs are contraindicated. The FFPRHC UK Medical Eligibility Criteria for Contraceptive Use specifically note current venous thromboembolism, current or past history of breast cancer, inflammatory bowel disease, and acute intermittent porphyria as conditions where the advantages of using emergency contraceptive pills generally outweigh the theoretical or proven risks.
The AAP, ACOG, FDA, WHO, FFPRHC and experts on emergency contraception say that ECPs, like all other contraceptives, reduce the absolute risk of ectopic pregnancy by preventing pregnancies, and that the best available evidence, obtained from over 7,800 women in randomized controlled trials, indicates there is no increase in the relative risk of ectopic pregnancy in women who become pregnant after using progestin-only ECPs.
Other common side effects (each reported by less than 20% of levonorgestrel-only users in both the 1998 and 2002 WHO trials) were abdominal pain, fatigue, headache, dizziness, and breast tenderness. Side effects usually do not occur for more than a few days after treatment, and they generally resolve within 24 hours.
Temporary disruption of the menstrual cycle is also commonly experienced. If taken before ovulation, the high doses of progestogen in levonorgestrel treatments may induce progestogen withdrawal bleeding a few days after the pills are taken. One study found that about half of women who used levonorgestrel ECPs experienced bleeding within 7 days of taking the pills. If levonorgestrel is taken after ovulation, it may increase the length of the luteal phase, thus delaying menstruation by a few days. Mifepristone, if taken before ovulation, may delay ovulation by 3-4 days. (Delayed ovulation may result in a delayed menstruation.) These disruptions only occur in the cycle in which ECPs were taken; subsequent cycle length is not significantly affected. If a woman's menstrual period is delayed by a week or more, it is advised that she take a pregnancy test. (Earlier testing may not give accurate results.)
ECPs are generally recommended for backup or "emergency" use, rather than as the primary means of contraception. They are intended for use when other means of contraception have failed—for example, if a woman has forgotten to take a birth control pill or when a condom is torn during sex.
The first widely used methods were five-day treatments with high-dose estrogens, using diethylstilbestrol (DES) in the US and ethinyl estradiol in the Netherlands.
In the early 1970s, the Yuzpe regimen was developed by AA Yuzpe (1974); progestin-only postcoital contraception was investigated (1975); and the copper IUD was first studied for use as emergency contraception (1975). Danazol was tested in the early 1980s in the hopes that it would have fewer side effects than Yuzpe, but was found to be ineffective.
The Yuzpe regimen became the standard course of treatment for postcoital contraception in many countries in the 1980s. The first prescription-only combined estrogen-progestin dedicated product, Schering PC4 (ethinylestradiol and norgestrel), was approved in the UK in January 1984 and first marketed in October 1984. Schering introduced a second prescription-only combined product, Tetragynon (ethinylestradiol and levonorgestrel) in Germany in 1985. By 1997, Schering AG dedicated prescription-only combined products had been approved in only 9 countries: the UK (Schering PC4), New Zealand (Schering PC4), South Africa (E-Gen-C), Germany (Tetragynon), Switzerland (Tetragynon), Denmark (Tetragynon), Norway (Tetragynon), Sweden (Tetragynon) and Finland (Neoprimavlar); and had been withdrawn from marketing in New Zealand in 1997 to prevent it being sold over-the-counter. Regular combined oral contraceptive pills (which were less expensive and more widely available) were more commonly used for the Yuzpe regimen even in countries where dedicated products were available.
Over time, interest in progestin-only treatments increased. The Special Program on Human Reproduction (HRP), an international organization whose members include the World Bank and World Health Organization, "played a pioneering role in emergency contraception" by "confirming the effectiveness of levonorgestrel. After the WHO conducted a large trial comparing Yuzpe and levonorgestrel in 1998, combined estrogen-progestin products were gradually withdrawn from some markets (Preven in the United States discontinued May 2004, Schering PC4 in the UK discontinued October 2001, and Tetragynon in France) in favor of progestin-only EC, although prescription-only dedicated Yuzpe regimen products are still available in some countries.
In 2002, China became the first country in which mifepristone was registered for use as EC.
The seven founding member organizations were the Concept Foundation, the International Planned Parenthood Federation (IPPF), the Pacific Institute for Women's Health, the World Health Organization (WHO), the Population Council, Population Services International, and the Program for Appropriate Technology in Health (PATH).
The Concept Foundation is the distribution arm of ICEC; its funding for the development of Postinor-2 came from the Rockefeller Foundation and the David and Lucile Packard Foundation, as well as the other ICEC organizations.
The Consortium helped promote the availability of EC by:
An ICEC member organization, the International Planned Parenthood Federation (IPPF), has launched its own dedicated levonorgestrel EC product, Optinor.
The current (October 2005) AAP Policy Statement on Emergency Contraception states: "The concern that widespread emergency contraception use would encourage unprotected coitus in teens is not supported in the literature."
The current (December 2005) ACOG Practice Bulletin on Emergency Contraception states: "A prominent concern among both women and health care providers is that making emergency contraception more readily available could encourage irresponsible sexual behavior, which would increase the risks of both unintended pregnancy and sexually transmitted diseases. However, numerous studies have shown that this concern is unfounded."
The latest (April 2007) review by emergency contraception experts Trussell and Raymond states: "Reported evidence demonstrates that making ECPs more widely available does not increase risk-taking and that women who are the most diligent about ongoing contraceptive use are those most likely to seek emergency treatment.
However, the availability of ECPs has not been shown to lower abortion rates. In France, Sweden, and Britain—where Yuzpe-regimen EC had been available by prescription for more than a decade and progestin-only EC has been available without a prescription for 8, 6, and 2 years respectively—the abortion rate was stable or higher during that time period. Another study concluded that distribution of free, advance supplies of EC to large numbers of women in Scotland did not reduce abortion rates. A randomized controlled trial of 2000 women in China compared women with advance access to EC to women without access, and noted that the pregnancy rate was the same between the two groups. The study observed that "...providing EC in advance increases use, but there is no direct evidence that it reduces unintended pregnancy" and concluded that EC may not lower abortion rates.
In September 2006, emergency contraception expert Anna Glasier wrote a BMJ editorial entitled "Emergency Contraception. Is it worth all the fuss?" that said in closing: "So is emergency contraception worth the fuss? If you are a woman who has had unprotected sex then of course it is, because emergency contraception will prevent pregnancy in some women some of the time—and if you don’t want to get pregnant anything is better than nothing. If you are the CMAJ’s editor or FDA commissioner then yes, because scientific freedom is worth the fight. If you are looking for an intervention that will reduce abortion rates, emergency contraception may not be the solution, and perhaps you should concentrate most on encouraging people to use contraception before or during sex, not after it."
Before EC was used in the general population or defined as "emergency contraception," it was used, beginning in the 1960s and 70s, specifically as a treatment for victims of sexual assault. Pregnancy rates among rape victims of child-bearing age are around 5%; in the U.S., about half of rape victims who become pregnant have abortions.Although EC is commonly used as an option for victims of sexual assault, some researchers believe such use is a public health measure that is not sufficiently widespread.
A number of studies in the 1970s and 80s concluded that emergency contraception could cause changes in the endometrium that would prevent implantation of an early-stage embryo in the uterus. This research led many pro-life advocates, who believe that pregnancy begins at fertilization, to oppose ECPs as an abortifacient.
In recent years—especially in light of U.S. ethical controversy over the research's claims—the scientific community has begun to critically reevaluate the early studies, introducing doubt into the argument that ECPs prevent implantation. Recent studies in rats and monkeys have shown that post-ovulatory use of progestin-only and combined ECPs have no effect on pregnancy rates. Studies in humans have shown that the rate of ovulation suppression is approximately equal to the effectiveness of emergency contraceptive pills, suggesting that might be the only mechanism by which they prevent pregnancy.
However, these studies have also shown that, in women who ovulate despite taking ECP before ovulation, there are changes in certain hormones such as progesterone and in the length of luteal phase. These secondary changes might inhibit implantation in cases where fertilization occurs despite ECP use. Because of the difficulty of studying embryos inside the uterus and fallopian tubes prior to implantation, both sides of this debate concede that completely proving or disproving the theory may be impossible.
When used as a regular method of contraception, IUDs have been proven to act primarily through spermicidal and ovicidal mechanisms, but it is considered possible that these same mechanisms are also harmful to embryos that have not yet implanted.
Hormonal progestin-only and combined estrogen-progestin emergency contraceptives such as Yuzpe regimen or Plan B are different from the anti-hormonal drug mifepristone (also known as Mifeprex and RU-486), an abortifacient which can induce abortion if taken after implantation. Yuzpe and progestin-only emergency contraception will have no effect if taken after implantation.