In a discovery that could reshape the debate over the French abortion pill, RU486, researchers have found it can enable women to avoid abortions by serving as a highly effective morning-after pill.
In a new study, Dr. Anna Glasier and her colleagues at the University of Edinburgh gave RU486 or a standard pregnancy-preventing regimen of high doses of birth control pills to 800 women who requested emergency help.
Both treatments prevented pregnancy in women who had had unprotected sexual intercourse in the preceding 72 hours, but RU486 caused far less nausea and vomiting, the study found.
Women who took RU486, however, were more likely to have a delay in the onset of their next menstrual period.
Four of the 398 women in the study who took the birth control pills became pregnant and none who took RU486 became pregnant, a difference that was statistically insignificant.
The investigators said that if no treatment had been given, they would have expected 17 pregnancies in each group. The study is being reported today in The New England Journal of Medicine.
Family planning experts hailed the study because it documented the effectiveness of high doses of birth control pills in preventing pregnancy, it might make women and their doctors aware that this method exists, and it showed that RU486 could be even better.
Some said they hoped that the new use for RU486, which is not available in the United States, would shift the debate over the drug away from the issue of abortion.
For those reasons, "It's an immensely important study," said Dr. Michael Policar, vice president for medical affairs at the Planned Parenthood Federation of America.
But opponents of abortion said that morning-after pills were, in fact, the moral equivalent of abortions. Saying otherwise "is more of the verbal gymnastics that pro-abortion advocates use so routinely," said Dr. Richard Glasow, the education director of the National Right to Life Committee.
The use of birth control pills as a morning-after drug has not been submitted to the Food and Drug Administration for review, so the pills cannot be advertised as having this effect.
However, since they have been approved for other purposes, doctors are free to prescribe them as a morning-after pill. Similarly, if RU486 were to be approved as a morning-after pill, doctors would be able to use it in abortions.
Dr. Policar said that most Planned Parenthood clinics, emergency rooms that treat women who have been sexually assaulted and many college health clinics prescribe morning-after birth control pills to prevent pregnancy.
The women are advised to take two pills, then wait 12 hours and take two more pills, Dr. Policar said. But, he added, "most health care professionals do not know" about the method.
Penny Murphy, a spokeswoman for the American College of Obstetricians and Gynecologists, said that there have not been been many studies to support the use of birth control pills as morning after pills. "And we know women haven't heard about it," she said.
Dr. David Grimes of the University of Southern California School of Medicine said the new study showed the advantage of using RU486.