Ella

Federal drug regulators on Friday approved a new form of emergency contraceptive pill that prevents pregnancies if taken as many as five days after unprotected intercourse.

The pill, called ella, will be available by prescription only. Developed in government laboratories, it is more effective than Plan B, the morning-after pill now available over the counter to women 17 and older.

That pill gradually loses efficacy and can be taken at most three days after sex. Ella, by contrast, works just as well on the fifth day as the first after sex.

Women who have unprotected intercourse have about 1 chance in 20 of becoming pregnant. Those who take Plan B within three days cut that risk to about 1 in 40, while those who take ella would cut that risk to about 1 in 50, regulators say. Studies show that ella is less effective in obese women.

The decision was greeted with enthusiasm by abortion rights groups and denounced by anti-abortion activists. But in recent years both sides have treated the emergency contraceptive pills as a side issue in the wider debate over abortion.

Studies have found that many women fail to realize they are at risk for an unplanned pregnancy after unprotected sex. So they tend not to use the emergency contraceptives even when they receive them free.

“Emergency contraception has no effect on pregnancy rates or abortion rates,” said Dr. James Trussell, director of the Office of Population Research at Princeton, who has consulted without charge for ella’s maker. “Women just don’t use them enough to make an impact.”

F.D.A. Approves 5-Day Emergency Contraceptive, The New York Times, august 13 2010.