Emergency contraception, sometimes referred to as the morning after pill, is birth control that can be used to prevent pregnancy after unprotected intercourse. The most widely-used emergency contraception drug is levonorgestrel, which is approved for use within 72 hours of sexual intercourse. A team of researchers from the U.S. and Europe has published new evidence supporting the use of ulipristal acetate as an effective alternative to levonorgestrel (marketed as Plan B®) for emergency contraception. This study was published online January 29, 2010 and also appears in the February 13 print edition of The Lancet.

The researchers studied over 2200 women with regular menstrual cycles who presented to family planning clinics requesting emergency contraception within 5 days of unprotected sexual intercourse. Study participants were randomly assigned to receive either a single dose of levonorgestrel or a single dose of ulipristal acetate by mouth. Among the 1700 women who received emergency contraception within 72 hours of intercourse, there were 37 pregnancies – 15 in the ulipristal acetate group and 22 in the levonorgestrel group. In 203 women who received emergency contraception between 72 hours and 120 hours after intercourse, there were three pregnancies, all among women in the levonorgestrel group.

This study confirms the results of an earlier trial in which ulipristal acetate was at least as effective as levonorgestrel in preventing pregnancy when taken up to 72 hours after sexual intercourse. It also provides additional evidence that ulipristal acetate is an effective alternative to emergency contraception that can be used to up 5 days after unprotected intercourse.

Source:

The Lancet. 2010; 375: 555-562.