Emergency contraception

Emergency contraception
Emergency contraception
Birth control type Hormonal (progestin or others) or intra-uterine
First use 1970s
Failure rates (per use)
Perfect use ECP: see article text
IUD: under 1%
Typical use 89%, 74%, 47%, 53%, or 83% (please see Effectiveness of ECPs below)%
User reminders Pregnancy test required if no period seen after 3 weeks
Clinic review Recommended to consider need screen STDs or consider ongoing routine contraceptive options
Advantages and disadvantages
STD protection No
Periods ECP may disrupt next menstrual period by couple days. IUDs may make menstruation heavier and more painful
Benefits IUDs may be subsequently left in place for ongoing contraception
Risks As per methods
Medical notes
Combined estrogrogen/progestin pills of Yuzpe regimen now superseded by better tolerated and more effective progestin-only pill.
Progestin only ECP licensed for use within 3 days of unprotected intercourse, Ulipristal acetate and IUDs within 5 days.

Emergency contraception (EC), or emergency postcoital contraception, refers to birth control measures that, if taken after sexual intercourse, may prevent pregnancy.

Forms of EC include:

  • Emergency contraceptive pills (ECPs)—sometimes simply referred to as emergency contraceptives (ECs) or the "morning-after pill"—are drugs intended to disrupt ovulation or fertilization in order to prevent pregnancy (contraceptives). There is controversy about whether such drugs may in some cases act not as a contraceptive but as a contragestive, a drug that prevents the implantation of a human embryo in the uterus, although one study has concluded that this mechanism is unlikely.[1][2][3][4]
  • Intrauterine devices (IUDs)—usually used as a primary contraceptive method, but sometimes used as emergency contraception.


Emergency contraceptive pills (ECPs)

Emergency contraceptive pills (sometimes referred to as emergency hormonal contraception (EHC) in Great Britain) may contain higher doses of the same hormones (estrogens, progestins, or both) found in regular combined oral contraceptive pills. Taken after unprotected sexual intercourse or contraceptive failure, such higher doses may prevent pregnancy from occurring.[5] Mifepristone can also be used as EC, though this drug is not considered an "emergency contraceptive pill." It is an anti-hormonal drug, and does not contain estrogen or progestins.[6]

The phrase "morning-after pill" is a misnomer; ECPs are effective when used shortly after intercourse. Depending on the drug, they are licensed for use for up to 107 to 120 hours after unprotected sexual intercourse or contraceptive failure.

Types of ECPs

The progestin-only method uses the progestin levonorgestrel in a dose of 1.5 mg, either as two 750 μg doses 12 hours apart, or more recently as a single dose. Progestin-only EC is available as a dedicated emergency contraceptive product under many names worldwide, including: in the U.S., Canada and Honduras as Plan B; in Great Britain, Ireland, Australia, New Zealand, Portugal and Italy as Levonelle; in South Africa as Escapelle; in 44 nations including France, most of Western Europe, India, and several countries in Africa, Asia and Latin America as NorLevo; and in 44 nations including most of Eastern Europe, Mexico and many other Latin American countries, Portugal, Australia and New Zealand, Israel, China, Hong Kong, Taiwan and Singapore as Postinor-2.[7] This pill typically works up to 72 hours after intercourse.[8]

The combined or Yuzpe regimen uses large doses of both estrogen and progestin, taken as two doses at a 12-hour interval. This method is now believed to be less effective and less well-tolerated than the progestin-only method.[9] It is possible to obtain the same dosage of hormones, and therefore the same effect, by taking several regular combined oral contraceptive pills. For example, 4 Ovral pills are the same as 4 Preven pills.[10][11] The United States Food and Drug Administration (FDA) approved this off-label use of certain brands of regular combined oral contraceptive pills in 1997.[5][10][12]

Ulipristal acetate (known as ella in the US and Ellaone in Europe) was approved as an ECP in Europe in early 2009 and in the US in August 2010. It works for up to 120 hours after intercourse.[8] It prevents pregnancy by delaying or inhibiting ovulation and inhibiting follicle rupture.[13] Watson Pharmaceuticals announced the availability of ella in the United States on December 1, 2010, in retail pharmacies, clinics and one online pharmacy, KwikMed.[14]

Emergency contraceptive pills (ECPs) are not to be confused with mifepristone (RU486, Mifeprex), which is used as an "abortion pill". The term "emergency contraceptive pill" does not refer to mifespristone, which is most commonly used in 200- or 600-mg doses as an abortifacient.[15] However, in China and Russia only,[13] mifepristone is available as either emergency contraception or as an abortifacient, depending on whether it is used before or after implantation. If used as emergency contraception, a low dose of mifepristone is slightly less effective than higher doses, but has fewer side effects.[16] As of 2000, the smallest dose available in the USA was 200 mg.[17] Mifepristone, however, is not approved for emergency contraceptive use in the United States.[18] A review of studies in humans concluded that the contraceptive effects of the 10-mg dose are due to its effects on ovulation,[19] but understanding of its mechanism of action remains incomplete. Higher doses of mifepristone can disrupt implantation and, unlike levonorgestrel, mifepristone can be effective in terminating established pregnancies.

Effectiveness of ECPs

The effectiveness of emergency contraception is presented differently from the effectiveness of ongoing methods of birth control: it is expressed as a percentage reduction in pregnancy rate for a single use of EC. Different ECP regimens have different effectiveness levels, and even for a single regimen different studies may find varying rates of effectiveness. Using an example of "75% effective", an article in American Family Physician explains the effectiveness calculation thus:

... 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.[20]

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."[21]

In 1999, a meta-analysis of eight studies of the combined (Yuzpe) regimen concluded that the best point estimate of effectiveness was 74%.[22] A 2003 analysis of two of the largest combined (Yuzpe) regimen studies, using a different calculation method, found effectiveness estimates of 47% and 53%.[23]

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.[9][24][25] 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.[26]

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%.[27] 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.[28]

History of calculation methods

Early studies of emergency contraceptives did not attempt to calculate a failure rate; they simply reported the number of women who became pregnant after using an emergency contraceptive. Since 1980, clinical trials of emergency contraception have first calculated probable pregnancies in the study group if no treatment were given. The effectiveness is calculated by dividing observed pregnancies by the estimated number of pregnancies without treatment.[29]

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. These are currently estimated using variants of the calendar method.[30] 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.[31]

Recently, hormonal assay has been suggested as a more accurate method of estimating fertility for EC studies.[32]


Existing pregnancy is not a contraindication in terms of safety, as there is no known harm to the woman, the course of her pregnancy, or the fetus if progestin-only or combined emergency contraception pills are accidentally used, but EC is not indicated for a woman with a known or suspected pregnancy because it is not effective in women who are already pregnant.[31][33][34][35][36][37][38][39]

The World Health Organization (WHO) lists no medical condition for which the risks of emergency contraceptive pills outweigh the benefits.[37] The American Academy of Pediatrics (AAP) and experts on emergency contraception have concluded that progestin-only ECPs may be preferable to combined ECPs containing estrogen in women with a history of blood clots, stroke, or migraine.[31][33][34]

The AAP, American College of Obstetricians and Gynecologists (ACOG), U.S. Food and Drug Administration, WHO, Royal College of Obstetricians and Gynaecologists, and other experts on emergency contraception state that there are no medical conditions in which progestin-only ECPs are contraindicated.[31][33][34][35][36][37][38] RCOG 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.[38]

The herbal preparation of St John's wort and some enzyme-inducing drugs (e.g. anticonvulsants or rifampicin) may reduce the effectiveness of ECP, and a larger dose may be required.[40][41]

The AAP, ACOG, FDA, WHO, RCOG, and experts on emergency contraception have concluded 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.[31][33][34][35][36][37][38][39][40][42]

Side effects

The most common side effect reported by users of emergency contraceptive pills was nausea (50.5% of 979 Yuzpe regimen users and 23.1% of 977 levonorgestrel-only users in the 1998 WHO trial; 14.3% of 2,720 levonorgestrel-only users in the 2002 WHO trial); vomiting is much less common and unusual with levonorgestrel-only ECPs (18.8% of 979 Yuzpe regimen users and 5.6% of levonorgestrel-only users in the 1998 WHO trial; 1.4% of 2,720 levonorgestrel-only users in the 2002 WHO trial).[9][26][40] Anti-emetics are not routinely recommended with levonorgestrel-only ECPs.[40][43] If a woman vomits within 2 hours of taking a levonorgestrel-only ECP, she should take a further dose as soon as possible.[40][44]

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.[9][26][40] Side effects usually do not occur for more than a few days after treatment, and they generally resolve within 24 hours.[31]

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.[45] If levonorgestrel is taken after ovulation, it may increase the length of the luteal phase, thus delaying menstruation by a few days.[46] Mifepristone, if taken before ovulation, may delay ovulation by 3–4 days.[47] (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.[45] If a woman's menstrual period is delayed by two weeks or more, it is advised that she take a pregnancy test.[48] (Earlier testing may not give accurate results.)

Availability by country

Intrauterine device (IUD) for emergency contraception

An alternative to emergency contraceptive pills is the copper-T intrauterine device (IUD) which can be used up to 5 days after unprotected intercourse to prevent pregnancy. Insertion of an IUD is more effective than use of Emergency Contraceptive Pills - pregnancy rates when used as emergency contraception are the same as with normal IUD use. IUDs may be left in place following the subsequent menstruation to provide ongoing contraception (3–10 years depending upon type).[49]

Postcoital high-dose progestin-only oral contraceptive pills as ongoing contraception

One brand of levonorgestrel pills, Postinor, was marketed as an ongoing method of postcoital contraception.[50] However, there are serious drawbacks to such use of postcoital high-dose progestin-only oral contraceptive pills, especially if they are not used according to their package directions, but are instead used according to the package directions of emergency contraceptive pills:

  • Due to the increasing severity of side effects with frequent use, Postinor is only recommended for women who have intercourse four or fewer times per month.[50][51]
  • If not used according to their package directions, but instead used according to the directions of levonorgestrel emergency contraceptive pills (up to 72 hours after intercourse), they would be estimated to have a "perfect-use" (when not used according to their package directions but used as directed on the package directions for levonorgestrel emergency contraception pills) pregnancy rate of 20% per year when used as the sole means of contraception (as compared to a 40% annual pregnancy rate for the Yuzpe regimen).[52] These failure rates would be higher than those of almost all other birth control methods, including the rhythm method and withdrawal.[53]
  • Like all hormonal methods, postcoital high-dose progestin-only oral contraceptive pills do not protect against sexually transmitted infections.[54]

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.[52]


The use of synthetic estrogens as a post coital contraceptive was discovered by Dr. John McLean Morris in 1966.[55][56] A few different drugs were studied, with a focus on high-dose estrogens, and it was originally hoped that postcoital contraception would prove viable as an ongoing contraceptive method.[57]

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.[58][59]

In the early 1970s, the Yuzpe regimen was developed by AA Yuzpe (1974);[60] progestin-only postcoital contraception was investigated (1975);[61] and the copper IUD was first studied for use as emergency contraception (1975).[62] 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.[63]

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.[64] Schering introduced a second prescription-only combined product, Tetragynon (ethinylestradiol and levonorgestrel) in Germany in 1985.[1] 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.[2][3][4] 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.[65]

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."[66] After the WHO conducted a large trial comparing Yuzpe and levonorgestrel in 1998,[67][68] 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.

United States & Canada

  • DES
    • In 1971, a New England Journal of Medicine editorial calling attention to previously published studies on the use of DES as a postcoital contraceptive at Yale University, and a large study published in JAMA on the use of DES as a postcoital contraceptive at the University of Michigan, led to off-label use of DES as a postcoital contraceptive becoming prevalent at many university health services.[69][70]
    • In May 1973, in an attempt to restrict off-label use of DES as a postcoital contraceptive to emergency situations such as rape, a FDA Drug Bulletin was sent to all U.S. physicians and pharmacists that said the FDA had approved, under restricted conditions, postcoital contraceptive use of DES.[71] (In February 1975, the FDA Commissioner testified that the only error in the May 1973 FDA Drug Bulletin was that the FDA had not approved postcoital contraceptive use of DES.)[72]
    • In September 1973, the FDA published a proposed rule specifying patient labeling and special packaging requirements for any manufacturer seeking FDA approval to market DES as a postcoital contraceptive, inviting manufacturers to submit abbreviated new drug applications (ANDAs) for that indication, and notifying manufacturers that the FDA intended to order the withdrawal of DES 25 mg tablets (which were being used off-label as postcoital contraceptives).[73][74][74][75]
    • In late 1973, Eli Lilly, the largest U.S. manufacturer of DES, discontinued its DES 25 mg tablets and in March 1974 sent a letter to all U.S. physicians and pharmacists telling them it did not recommend use of DES as a postcoital contraceptive.[72]
    • Only one pharmaceutical company, Tablicaps, Inc., a small manufacturer of generic drugs, ever submitted (in January 1974) an ANDA for use of DES as an emergency postcoital contraceptive, and the FDA never approved it.[72][76]
    • In February 1975, the FDA said it had not yet approved DES as a postcoital contraceptive, but would after March 8, 1975 permit marketing of DES for that indication in emergency situations such as rape or incest if a manufacturer obtained an approved ANDA that provided patient labeling and special packaging as set out in a FDA final rule published in February 1975.[77] To discourage off-label use of DES as a postcoital contraceptive, in February 1975 the FDA ordered DES 25 mg (and higher) tablets removed from the market and ordered the labeling of lower doses (5 mg and lower) of DES still approved for other indications be changed to state: "THIS DRUG PRODUCT SHOULD NOT BE USED AS A POSTCOITAL CONTRACEPTIVE" in block capital letters on the first line of the physician prescribing information package insert and in a prominent and conspicuous location of the container and carton label.[74][78]
    • In March 1978, a FDA Drug Bulletin was sent to all U.S. physicians and pharmacists which said: "FDA has not yet given approval for any manufacturer to market DES as a postcoital contraceptive. The Agency, however, will approve this indication for emergency situations such as rape or incest if a manufacturer provides patient labeling and special packaging. To discourage 'morning after' use of DES without patient labeling, FDA has removed from the market the 25 mg tablets of DES, formerly used for this purpose."[79]
    • In the 1980s, off-label use of the Yuzpe regimen superseded off-label use of DES for postcoital contraception.[76][80][81]
    • DES is no longer commercially available in the U.S.; Eli Lilly, the last U.S. manufacturer, ceased production in spring 1997.[82]
  • Yuzpe regimen & Preven
    • On February 25, 1997, the FDA posted a notice in the Federal Register saying it had concluded that the Yuzpe regimen was safe and effective for off-label use as postcoital EC, was prepared to accept NDAs for COCPs labeled as ECPs, and listed 6 then available COCPs (there are now 22) that could be used as ECPs.[10][83]
    • On September 1, 1998, the FDA approved the prescription Yuzpe regimen Preven Emergency Contraception Kit (which contained a urine pregnancy test and 4 COCPs).[84] Preven was discontinued in May 2004.[85]
  • Plan B
    • On July 28, 1999, the FDA approved the prescription progestin-only Plan B (two 750 µg levonorgestrel pills) emergency contraceptive.[86]
    • On August 24, 2006, the FDA approved nonprescription behind-the-counter access to Plan B from pharmacies staffed by a licensed pharmacist for women 18 or older; a prescription-only form of Plan B was made available for younger females aged 17 and younger.[87]
    • On November 6, 2006, Barr Pharmaceuticals announced that its subsidiary, Duramed Pharmaceuticals, had initiated shipment of dual-label Plan B OTC/Rx and it would be available in pharmacies across the U.S. by mid-November 2006.[88]
    • On March 23, 2009, a US judge ordered the FDA to allow 17 year olds to acquire Plan B without a prescription.[89] This now changes the August 24, 2006 ruling and Plan B is now available "behind the counter" for men and women. There is a prescription method available for girls under 17.

International Consortium for Emergency Contraception

In 1995, the Rockefeller Foundation convened a meeting to discuss emergency contraception. After the meeting, a group of seven international organizations formed The International Consortium for Emergency Contraception (ICEC) to promote EC as a part of mainstream reproductive health care worldwide.[90] Dedicated products for EC were "virtually unknown" in 1995, there was little awareness of EC as an option, and EC was not used as public health measure.[91]

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).[90]

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.[92]

The Consortium helped promote the availability of EC by:[91]

  • Manufacturing an EC product. The ICEC worked with the Hungarian pharmaceutical firm Gedeon Richter to repackage its contraceptive Postinor as an emergency contraceptive, called Postinor-2. Distributing Postinor-2, principally in developing countries, was the primary work of the ICEC.
  • Facilitating product registration in two ways. First, the ICEC encouraged interest in EC products through meetings with public-sector agencies and non-governmental organizations (NGOs) who they perceived would benefit from adding EC to the products they distribute. Second, by helping organizations applying for EC registration through the country-specific approval process, including lobbying of local leaders who may be influential in the registration decision.
  • Negtiotiating a public-sector price. The ICEC's agreement with Gedeon Richter provided a discount price at which EC could be obtained by public-sector agencies in developing countries.
  • Marketing and social marketing.

An ICEC member organization, the International Planned Parenthood Federation (IPPF), has launched its own dedicated levonorgestrel EC product, Optinor.[93]

Relationship to high risk sex and abortion

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."[33]

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."[35]

The latest (April 2007) review by emergency contraception experts Trussell and Raymond[31] states: "Reported evidence demonstrates that making ECPs more widely available does not increase risk-taking[94][95][96][97][98][99][100][101][102][103][104] and that women who are the most diligent about ongoing contraceptive use are those most likely to seek emergency treatment."[105]

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.[106] Another study concluded that distribution of free, advance supplies of EC to large numbers of women in Scotland did not reduce abortion rates.[107] 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.[108]

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 CMAJs 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."[109]

EC and sexual assault

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.[110][111] 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.[112] 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.[113]

Mechanism of action

The United States FDA states that progestin-only ECPs like Plan B work by preventing ovulation. It also says "it is possible" that progestin-only ECPs may interfere with the blastocyst implanting in the uterine lining, and that they have no effect on pregnancies if taken after implantation.[114][115]

A number of studies in the 1970s and 80s concluded that emergency contraception could cause changes in the endometrium[116] 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. Recent studies in rats and monkeys have shown that post-ovulatory use of progestin-only and combined ECPs have no effect on pregnancy rates.[117][118] Studies in humans have shown that the rate of ovulation suppression is approximately equal to the effectiveness of emergency contraceptive pills,[119][120] 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.[119] These secondary changes might inhibit implantation in cases where fertilization occurs despite ECP use. Because of the difficulty of studying zygotes 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.[117][121]

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 zygotes that have not yet implanted.[122]

Hormonal progestin-only and combined estrogen-progestin emergency contraceptives such as Yuzpe regimen or Plan B differ from the anti-hormonal drug mifepristone (also known as Mifeprex and RU-486). Yuzpe and progestin-only emergency contraception will have no effect if taken after implantation, whereas mifepristone can induce abortion if taken after implantation.

United States legal and ethical controversies

A great deal of controversy accompanied the FDA approval of over-the-counter (OTC) access to Plan B. Supporters of over-the-counter access believe that easier access will reduce unintended pregnancy and abortion rates; some abortion opponents believe that EC itself is a form of abortion.[123] The American Medical Association, the American Academy of Family Physicians, the American College of Obstetricians and Gynecologists, the American Academy of Pediatrics, and other leading U.S. medical organizations all supported OTC access.[124] An advisory committee to the FDA recommended that Plan B be made available over the counter in 2003.[125] In 2004, the FDA refused the advisory board's recommendation and prohibited over-the-counter sale, citing insufficient evidence that ECPs could be used safely by adolescents without medical supervision. Reproductive rights supporters accused the FDA of basing the decision on political pressure from the pro-life lobby. The Center for Reproductive Rights filed a lawsuit regarding the approval process, which had not been resolved as of December 2006. In the legal proceedings, two senior FDA officials alleged in depositions that the decision to reject the OTC application was made on political, rather than scientific, grounds to "appease the administration's constituents".[126][127] Depositions taken from other FDA officials do not indicate White House involvement.[126] In 2006, the FDA approved over-the-counter access to Plan B for women 18 years of age and older.[128] In April 2009, the FDA followed the ruling of a New York Federal District Court and loosened the restrictions to allow Duramed Pharmaceuticals to provide Plan B without a prescription to 17-year-olds. However, as of June 2009, Duramed had not yet put a non-prescription Plan B product for 17-year-olds through FDA approval, a process that could take some time.[129]

A Massachusetts law that went into effect on 14 December 2005 requires all hospitals in the state to provide emergency contraception to any "female rape victim of childbearing age"[130] including Catholic Hospitals who oppose the provision of emergency contraception. In a letter criticizing the joint UN/WHO Inter-agency Field Manual on Reproductive Health in Refugee Situations, the Catholic Church explains its belief that emergency contraception, along with IUDs and hormonal contraception, cannot be considered "solely contraceptive because in the case of effective fertilization a chemical abortion would be carried out during the first days of pregnancy."[131] The Catholic position on family planning is explained further in Ethical and Religious Directives for Catholic Health Care Services.[132] Because of this expressed moral stance against emergency contraception, the Massachusetts Catholic Conference opposed this law, stating interference with religious freedom. According to The New England Journal of Medicine, "compelling arguments can be made both for and against a pharmacist's right to refuse prescriptions for emergency contraception."[133]

In isolated instances across the United States, pharmacists have refused to dispense emergency contraception even when presented with a legal prescription.[134] In 2010, the Washington State Pharmacy Board decided that pharmacists do have a right to refuse to dispense emergency contraception.[135] In addition, Wal-Mart, the nation's fifth-largest distributor of pharmaceuticals, refused to stock EC, beginning with Preven in 1999.[136] However, Wal-Mart reversed this position when it was announced that stores would sell Plan B in March 2006.[137]

The Congregation for the Doctrine of the Faith in the 2008 Instruction Dignitas Personae(Paragraph 23) stated that: "Alongside methods of preventing pregnancy which are, properly speaking, contraceptive, that is, which prevent conception following from a sexual act, there are other technical means which act after fertilization, when the embryo is already constituted, either before or after implantation in the uterine wall. Such methods are interceptive if they interfere with the embryo before implantation and contragestative if they cause the elimination of the embryo once implanted...Therefore, the use of means of interception and contragestation fall within the sin of abortion and are gravely immoral. Furthermore, when there is certainty that an abortion has resulted, there are serious penalties in canon law." [138]

See also

  • Rape crisis center
  • Ulipristal acetate - Another emergency contraceptive, marketed as Ella, was approved in the U.S. in 2010, and is effective up to five days after sex


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