Plan B - Emergency Contraception

Emergency contraceptive pills (ECPs), are an oral drug containing high doses of the same hormones found in regular oral contraceptive pills, which, when taken after unprotected sexual intercourse, may prevent pregnancy from occurring.

There are several mechanisms of action by which such drugs may work. Depending on the time during the menstrual cycle that they are taken, this drug may inhibit or delay ovulation, inhibit tubal transport of the ovum or sperm cell, or interfere with fertilization.

In cases where it fails to prevent fertilization, it may prevent implantation; however, studies into the method of action of progestin-only ECP have called into question whether ECPs do actually disrupt or prevent implantation.

In this respect, emergency contraceptive pills work by triggering the same hormonal changes in the body as regular birth control pills or even breastfeeding — but they require much higher doses and are less effective than ongoing hormonal contraceptives.

The phrase "morning-after pill" is a misnomer that is falling out of use due to the fact they are licensed for use up to 72 hours after sexual intercourse. Emergency contraception or "emergency contraceptive pills" is the phrase preferred by the medical community. Unlike chemical abortion, emergency contraception does not end pregnancies and will not harm a developing embryo.

Emergency Contraception Pills

Types of Emergency Contraception Pills
Emergency hormonal contraception was available in two main forms: the original version was the combined or Yuzpe regimen which uses large doses of both estrogen and progestin taken as two doses at twelve hour intervals. This technique is believed to be approximately 75% effective depending on how soon it is taken after unprotected intercourse. With this regimen being less effective, and causing more side effects, than the more recently introduced progestin-only method, specific products have been withdrawn (Preven in the United States discontinued May 2004, Schering PC4 in the United Kingdom discontinued October 2001, and Tetragynon in France). Medical Information

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. This method is now known to be more effective (up to 89%) and better tolerated (less nausea or vomiting) than the Yupze method [2], and is available in the U.S. and Canada as Plan B, in the UK as Levonelle, and in France as NorLevo.

"Dedicated products" such as Plan B and Levonelle are specifically designed and marketed as emergency contraceptive pills. It is also possible to obtain the same dosage of hormones, and therefore the same effect, by taking a number of regular progestin-only or combined estrogen-progestin oral contraceptive pills.

Side effects of Emergency Contraception Pills
The most common side effect of emergency contraception pills are nausea, abdominal pain, fatigue, headache, dizziness, vomiting, and breast tenderness. These side effects are normally resolved within 24 hours. The rate of these effects occurring is less for progestin-only pills when compared to combined pills.

Also common is temporary disruption of the menstrual cycle, which may manifest as early or late periods, spotting or breakthrough-bleeding, and (less commonly) missed periods. The primary mechanism of EC is delaying ovulation. Menstruation occurs on average 14 days after ovulation, so a delayed ovulation will result in a delayed menstruation. Suppression of ovulation may cause anovulatory bleeding, which could manifest as an early period.