Emergency contraception
Emergency contraception is a birth control measure, used after sexual intercourse to prevent pregnancy.
There are different forms of EC. Emergency contraceptive pills, sometimes simply referred to as emergency contraceptives, or the morning-after pill, are medications intended to disrupt or delay ovulation or fertilization, which are necessary for pregnancy.
Intrauterine devices usually used as a primary contraceptive methodare sometimes used as the most effective form of emergency contraception. However, the use of IUDs for emergency contraception is relatively rare.
Definition
Emergency contraception is a birth control measure taken to reduce the risk of pregnancy following unprotected sexual intercourse or when other regular contraceptive measures have not worked properly or have not been used correctly. It is intended to be used occasionally and is not the same as medical abortion. Emergency contraception is offered to women who do not wish to conceive but have had unprotected sex on any day of the menstrual cycle, from day 21 after giving birth, or from day five after abortion or miscarriage. Emergency contraception measures include tablets taken by mouth or the insertion of a copper intrauterine device.Emergency contraception is not related to medical abortion, which is a drug regimen administered to terminate pregnancies in any trimester.
Emergency contraceptive pills
Emergency contraceptive pills are sometimes referred to as emergency hormonal contraception. They are taken after unprotected sexual intercourse or the breakage of a condom.Types
A variety of emergency contraceptive pills are available, including combined estrogen and progestin pills; progestin-only pills; and antiprogestin pills. Progestin-only and anti-progestin pills are available as specifically packaged pills for use as emergency contraceptive pills. Emergency contraceptive pills originally contained higher doses of the same hormones found in regular combined oral contraceptive pills. Combined estrogen and progestin pills are no longer recommended as dedicated emergency contraceptive pills, but certain regular combined oral contraceptive pills have also been shown to be effective as emergency contraceptive pills.Progestin-only emergency contraceptive pills contain levonorgestrel, either as a single tablet, effective up to 72 hours after intercourse. Progestin-only ECPs are sold under many different brand names. Progestin-only ECPs are available over-the-counter in many countries, from a pharmacist without a prescription, and available with a prescription in some other countries.
The antiprogestin ulipristal acetate is available as a micronized emergency contraceptive tablet, effective up to 120 hours after intercourse. Ulipristal acetate ECPs developed by HRA Pharma are available over the counter in Europe and by prescription in over 50 countries under the brand names ellaOne, ella, Duprisal 30, Ulipristal 30, and UPRIS.
The antiprogestin mifepristone is available in five countries as a low-dose or mid-dose emergency contraceptive tablet, effective up to 120 hours after intercourse. Low-dose mifepristone ECPs are available by prescription in Armenia, Russia, Ukraine, and Vietnam and from a pharmacist without a prescription in China. Mid-dose mifepristone ECPs are available by prescription in China and Vietnam.
Combined estrogen and progestin pills used to be available as dedicated emergency contraceptive pills under several brand names: Schering PC4, Tetragynon, Neoprimavlar, and Preven but were withdrawn after more effective dedicated progestin-only emergency contraceptive pills with fewer side effects became available. If other more effective dedicated emergency contraceptive pills are not available, specific combinations of regular combined oral contraceptive pills can be taken in split doses 12 hours apart, effective up to 72 hours after intercourse.
The U.S. Food and Drug Administration approved this off-label use of certain brands of regular combined oral contraceptive pills in 1997. As of 2014, there are 26 brands of regular combined oral contraceptive pills containing levonorgestrel or norgestrel available in the United States that can be used in the emergency contraceptive Yuzpe regimen, when none of the more effective and better-tolerated options are available.
Effectiveness
Ulipristal acetate, and mid-dose mifepristone are both more effective than levonorgestrel, which is more effective than the Yuzpe method.The effectiveness of emergency contraception is expressed as a percentage reduction in pregnancy rate for a single use of EC. Using an example of "75% effective", the effectiveness calculation thus:
The progestin-only regimen has an 89% effectiveness. , 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 regimen concluded that the best point estimate of effectiveness was 74%. A 2003 analysis of two of the largest combined 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.
The World Health Organization suggested that reasonable effectiveness may continue for up to 120 hours after intercourse.
For 10 mg of mifepristone taken up to 120 hours after intercourse, the combined estimate from three trials was an effectiveness of 83%. A review found that a moderate dose of mifepristone is better than LNG or Yuzpe, with delayed return of menstruation being the main adverse effect of most regimes.
HRA Pharma changed its packaging information for Norlevo in November 2013 warning that according to studies the drug loses effectiveness in women who weigh more than 75 kg and is completely ineffective for women who weigh over 80 kg. After a review by European Medicines Agency, the statement was deleted from the leaflet. The agency communicated that levonorgestrel is safe and effective method of emergency contraception, regardless of body weight.
Safety
The most common side effect reported by users of emergency contraceptive pills was nausea, reported by 14 to 23% of levonorgestrel-only users and 50.5% of Yuzpe regimen users. Vomiting is much less common and unusual with levonorgestrel-only ECPs. Anti-emetics are not routinely recommended with levonorgestrel-only ECPs. If a woman vomits within 2 hours of taking a levonorgestrel-only ECP, she should take a further dose as soon as possible.Other common side effects were abdominal pain, fatigue, headache, dizziness, and breast tenderness. Side effects generally resolve within 24 hours, although temporary disruption of the menstrual cycle is 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. 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 two weeks or more, it is advised that she take a pregnancy test.
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.
The World Health Organization lists no medical condition for which the risks of emergency contraceptive pills outweigh the benefits. The American Academy of Pediatrics and experts on emergency contraception have concluded that progestin-only ECPs are preferable to combined ECPs containing estrogen for all women, and particularly those with a history of blood clots, stroke, or migraine.
There are no medical conditions in which progestin-only ECPs are contraindicated. Current venous thromboembolism, current or history of breast cancer, inflammatory bowel disease, and acute intermittent porphyria are conditions where the advantages of using emergency contraceptive pills generally outweigh the theoretical or proven risks.
ECPs, like all other contraceptives, reduce the absolute risk of ectopic pregnancy by preventing pregnancies and there is no increase in the relative risk of ectopic pregnancy in women who become pregnant after using progestin-only ECPs.
Interactions
The herbal preparation of St John's wort and some enzyme-inducing drugs may reduce the effectiveness of ECP, and a larger dose may be required, especially in women who weigh more than 165 lbs.Intrauterine device
An effective emergency contraception measure is the copper-T intrauterine device which is generally recommended up to 5 days after unprotected intercourse or up to 5 days after probable ovulation. Some studies have found it to be effective up to 10 days after unprotected intercourse to prevent pregnancy. A 2021 study found that the hormonal IUD was as effective at emergency contraception as the copper IUD, though it is not offered by clinicians at the moment due to the lack of research done into the subject.Insertion of an IUD is more effective than the use of emergency contraceptive pillspregnancy rates when used as emergency contraception are the same as with normal IUD use. Unlike emergency contraceptive pills, which work by delaying ovulation, the copper-T IUD works by interfering with sperm motility. Therefore, the copper IUD is equally effective as emergency contraception at all weight ranges. IUDs may be left in place following the subsequent menstruation to provide ongoing contraception for as long as desired.