WASHINGTON, D.C.: The Food and Drug Administration said that specific does of certain oral contraceptives can be safely and effectively used as "morning-after pills." According to FDA studies, taking two two oral contraceptives within 72 hours after intercourse, followed by a second identical dose 12 hours later, is 75 percent effective in blocking a pregnancy. The pills work by preventing a fertilized egg from entering the uterus and won't work if a woman is already pregnant. Aside from nausea and, in some cases, vomiting, there are no serious side effects. It's the first federal approval of an emergency contraception method that has been prescribed for the past decade in Europe. While the United Kingdom approved the first emergency contraception method in 1984, and several European countries followed, until now no birth-control products had been officially approved for such use in the U.S. In part this was because drug companies, fearing lawsuits and protests from anti-abortion groups, had been reluctant to package or promote their pills as safe for use after sex. The companies are still reluctant: The FDA, in a highly unusual action, approved a new use for the drug even though the manufacturers hadn't asked the agency to. Approved brands include Wyeth-Ayerst Laboratories' Ovral, Lo/Ovral, Nordette and Triphasil, and Berlex Laboratories Levlen and Tri-Levlen. Wyeth said that despite the announcement, it would not market pills as a "morning-after" product in the U.S. Although emergency contraception is not an abortive drug, many anti-abortion groups still oppose it. Serrin Foster, president of Feminists for Life of America, says that because the drug prevents the fertilized egg from developing, it is a form of abortion. "We consider life to begin from the very first moments," Foster said. Dr. Matthew Bulfin, a member of the American Association of Pro-Life Obstetricians and Gynecologists, takes a different view. He has long prescribed what he calls the "morning after" pill to patients at his Florida practice. "My own view is that it's infinitely better than abortion," he said. "I think if it is publicized and widely used it will drastically decrease the number of abortions performed every year."