Emergency contraception

Copper IUD within 5 to 10 daysUlipristal acetate or mifepristone pill within 5 days Levonorgestrel pill within 3 days Emergency contraception (EC) are birth control measures that may be used after sexual intercourse to prevent pregnancy. Emergency contraception has not been shown to affect the rates of abortion within a country.... 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.Calculation of effectiveness, and particularly the denominator of the fraction, involves many assumptions that are difficult to validate...The risk of pregnancy for women requesting ECPs appears to be lower than assumed in the estimates of ECP efficacy, which are consequently likely to be 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.Mechanism of actionCopper-releasing IUCsWhen used as a regular or emergency method of contraception, copper-releasing IUCs act primarily to prevent fertilization. Emergency insertion of a copper IUC is significantly more effective than the use of ECPs, reducing the risk of pregnancy following unprotected intercourse by more than 99%.2,3 This very high level of effectiveness implies that emergency insertion of a copper IUC must prevent some pregnancies after fertilization.Emergency contraceptive pillsTo make an informed choice, women must know that ECPs—like the birth control pill, patch, ring, shot, and implant,76 and even like breastfeeding77—prevent pregnancy primarily by delaying or inhibiting ovulation and inhibiting fertilization, but may at times inhibit implantation of a fertilized egg in the endometrium. However, women should also be informed that the best available evidence indicates that ECPs prevent pregnancy by mechanisms that do not involve interference with post-fertilization events.ECPs do not cause abortion78 or harm an established pregnancy. Pregnancy begins with implantation according to medical authorities such as the US FDA, the National Institutes of Health79 and the American College of Obstetricians and Gynecologists (ACOG).80Ulipristal acetate (UPA). One study has demonstrated that UP can delay ovulation.81... Another study found that UPA altered the endometrium, but whether this change would inhibit implantation is unknown.82p. 122:Progestin-only emergency contraceptive pills. Early treatment with ECPs containing only the progestin levonorgestrel has been show to impair the ovulatory process and luteal function.83–87p. 123:Combined emergency contraceptive pills. Several clinical studies have shown that combined ECPs containing ethinylestradiol and levonorgestrel can inhibit or delay ovulation.107–110How does EC work?In 2002, a judicial review ruled that pregnancy begins at implantation, not fertilisation.8 The possible mechanisms of action should be explained to the patient as some methods may not be acceptable, depending on individual beliefs about the onset of pregnancy and abortion.Copper-bearing intrauterine device (Cu-IUD). Copper is toxic to the ovum and sperm and thus the copper-bearing intrauterine device (Cu-IUD) is effective immediately after insertion and works primarily by inhibiting fertilisation.9–11 A systematic review on mechanisms of action of IUDs showed that both pre- and postfertilisation effects contribute to efficacy.11 If fertilisation has already occurred, it is accepted that there is an anti-implantation effect,12,13Levonorgestrel (LNG). The precise mode of action of levonorgestrel (LNG) is incompletely understood but it is thought to work primarily by inhibition of ovulation.16,17Ulipristal acetate (UPA). UPA’s primary mechanism of action is thought to be inhibition or delay of ovulation.2Can LNG ECPs cause an abortion?LNG ECPs do not interrupt an established pregnancy or harm a developing embryo.15 The evidence available to date shows that LNG ECP use does not prevent a fertilized egg from attaching to the uterine lining. The primary mechanism of action is to stop or disrupt ovulation; LNG ECP use may also prevent the sperm and egg from meeting.16Emergency postcoital contraceptionLevonorgestrelMechanism and efficacy There is strong evidence that treatment with emergency contraception acts primarily by preventing or delaying ovulation and by preventing fertilization.22–26 Studies have indicated that emergency contraception does not prevent implantation.27–29 Experiments in monkeys and rats could detect no effect of a high dose of levonorgesterel administered postcoitally once fertilization had occurred.30,31 The evidence indicates that a postfertilization effect does not contribute to the efficacy of emergency contraception.25,30–33 Clinicians, pharmacists, and patients can be reassured that treatment with emergency contraception is not an abortifacient.p. 157:The use of progesterone receptor modulators for emergency contraception Mifepristone. In randomized trials, 10 mg mifepristone was as effective as 25, 50, or 600 mg. preventing about 80-85% of expected pregnancies (the same efficacy and side effects as with the levonorgestrel method), with a slight decrease in efficacy when treatment was delayed to 5 days after intercourse.16,52–54Ulipristal Acetate. Ulipristal acetate (ellaOne) has similar biologic effects as mifepristone and is approved for emergency contraception in Europe and is expected to become available in the U.S.in a single oral dose of 30 mg. Randomized trials demonstrated that ulipristal acetate is slightly more effective than the single 1.5 mg dose of levonorgestrel when used within 72 h after sexual intercourse and even between 72 h and 120h.55,56 … Progesterone receptor modulators like ulipristal acetate and mifepristone suppress ovarian follicular growth and also delay endometrial maturation, manifested in a delay in menstruation after treatment. Ovulation can be temporarily postponed.Other methodsAnother method of emergency contraception is the insertion of a copper IUD, anytime during the preovulatory phase of the menstrual cycle and up to 5 days after ovulation. The failure rate (in a small number of studies) is very low, 0.1%.34,35 This method definitely prevents implantation, but it is not suitable for women who are not candidates for intrauterine contraception, e.g., multiple sexual partners or a rape victim. The use of a copper IUD for emergency contraception is expensive, but not if it is retained as an ongoing method of contraception.Emergency contraceptionIt is believed that the main mechanism of action of high-dose progestin emergency contraception is inhibition of ovulation, but other mechanisms may be involved... Taken together, these data are highly supportive of the concept that levonorgestrel emergency contraception has little or no effect on postovulation events but is highly effective when taken before ovulation. Levonorgestrel emergency contraception does not affect implantation and is not abortifacient.Intrauterine insertion of a copper IUD within 5 to 10 days of midcycle coitus is a very effective method of preventing continuation of the pregnancy… The LNG-IUS should not be used for emergency contraception.A study by the WHO reported that use of a single tablet of 10 mg of mifepristone was an effective emergency contraceptive with a pregnancy rate of 1.2%.Ulipristal, also known as CDB-2914, has been studied as an emergency contraceptive pill… In 2009, European regulatory approval was granted for a 30-mg tablet of ulipristal (under the brand name of EllaOne) as an emergency contraceptive pill for use up to 5 days after unprotected intercourse. An application for approval in the United States is under review.Levonorgestrel-only emergency contraceptive pills:• Interfere with the process of ovulation;• May possibly prevent the sperm and the egg from meeting.Implications of the research:• Inhibition or delay of ovulation is LNG ECPs principal and possibly only mechanism of action.• Review of the evidence suggests that LNG ECPs cannot prevent implantation of a fertilized egg. Language on implantation should not be included in LNG ECP product labeling.• The fact that LNG ECPs have no demonstrated effect on implantation explains why they are not 100% effective in preventing pregnancy, and are less effective the later they are taken. Women should be given a clear message that LNG ECPs are more effective the sooner they are taken.• LNG ECPs do not interrupt a pregnancy (by any definition of the beginning of pregnancy). However, LNG ECPs can prevent abortions by reducing unwanted pregnancies. Emergency contraception (EC) are birth control measures that may be used after sexual intercourse to prevent pregnancy. Emergency contraception has not been shown to affect the rates of abortion within a country. There are different forms of EC. Emergency contraceptive pills (ECPs)—sometimes simply referred to as emergency contraceptives (ECs) or the morning-after pill—are medications intended to disrupt or delay ovulation or fertilization, which are necessary for pregnancy. ECPs and abortion pills are not the same. ECPs work by preventing or delaying ovulation and therefore preventing pregnancy, not by abortion. Intrauterine devices (IUDs)—usually used as a primary contraceptive method, are sometimes used as the most effective form of emergency contraception. However, use of IUDs for emergency contraception is relatively rare. Emergency contraceptive pills (ECPs) (sometimes referred to as emergency hormonal contraception, EHC) are taken after unprotected sexual intercourse or breakage of a condom. A variety of types of emergency contraceptive pills are available: combined estrogen and progestin pills, progestin-only (levonorgestrel, LNG) pills, and antiprogestin (ulipristal acetate or mifepristone) pills. Progestin-only and antiprogestin pills are available specifically packaged for use as emergency contraceptive pills. Emergency contraceptive pills originally contained higher doses of the same hormones (estrogens, progestins, or both) found in regular combined oral contraceptive pills. Combined estrogen and progestin pills are no longer recommended as dedicated emergency contraceptive pills (because this regimen is less effective and caused more nausea), but certain regular combined oral contraceptive pills (taken 2-5 at a time in what was called 'the Yuzpe regimen') have also been shown to be effective as emergency contraceptive pills. Progestin-only emergency contraceptive pills contain levonorgestrel, either as a single tablet (or historically, as a split dose of two tablets taken 12 hours apart), 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 (OTC) in many countries (e.g. Australia, Bangladesh, Bulgaria, Canada, Cyprus, Czech Republic, Denmark, Estonia, India, Malta, Netherlands, Norway, Portugal, Romania, Slovakia, South Africa, Sweden, United States), 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 (marketed by Watson Pharmaceuticals in the United States), Duprisal 30, Ulipristal 30, and UPRIS. The antiprogestin mifepristone (also known as RU-486) 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 (ethinylestradiol) and progestin (levonorgestrel or norgestrel) pills used to be available as dedicated emergency contraceptive pills under several brand names: Schering PC4, Tetragynon, Neoprimavlar, and Preven (in the United States) but were withdrawn after more effective dedicated progestin-only (levonorgestrel) emergency contraceptive pills with fewer side effects became available. If other more effective dedicated emergency contraceptive pills (levonorgestrel, ulipristal acetate, or mifepristone) are not available, specific combinations of regular combined oral contraceptive pills can be taken in split doses 12 hours apart (the Yuzpe regimen), effective up to 72 hours after intercourse. The U.S. Food and Drug Administration (FDA) 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. Ulipristal acetate, and mid-dose mifepristone are both more effective than levonorgestrel, which is more effective than the Yuzpe method.