The Patient information leaflet inside Emergency Hormonal Contraceptives (EHC) - medicines widely used to prevent pregnancy after sex, say they may work by blocking fertilized eggs from implanting in a woman’s uterus.
A new examination of the evidence in the US by the The New York Times has found that the federally approved labels and medical Web sites do not reflect what the science shows. Studies have not established that emergency contraceptive pills prevent fertilized eggs from implanting in the womb, leading scientists say. Rather, the pills delay ovulation, the release of eggs from ovaries that occurs before eggs are fertilized, and some pills also thicken cervical mucus so sperm have trouble swimming.
It turns out that the politically charged debate over morning-after pills and abortion, a divisive issue in this election year, is probably rooted in outdated or incorrect scientific guesses about how the pills work. Because they block creation of fertilized eggs, they would not meet abortion opponents’ definition of abortion-inducing drugs. In contrast, RU-486, a medication prescribed for terminating pregnancies, destroys implanted embryos.
The notion that morning-after pills prevent eggs from implanting stems from the Food and Drug Administration’s decision during the drug-approval process to mention that possibility on the label — despite lack of scientific proof, scientists say, and objections by the manufacturer of Plan B, the pill on the market the longest. Leading scientists say studies since then provide strong evidence that Plan B does not prevent implantation, and no proof that a newer type of pill, Ella, does. Some abortion opponents said they remain unconvinced.
After The Times asked about this issue, A.D.A.M., the firm that writes medical entries for the National Institutes of Health Web site, deleted passages suggesting emergency contraceptives could disrupt implantation. The Times, which uses A.D.A.M.’s content on its health Web page, updated its site. The medical editor in chief of the Web site for the Mayo Clinic, Dr. Roger W. Harms, said “we are champing at the bit” to revise the entry if the Food and Drug Administration changes labels or other agencies make official pronouncements.
“These medications are there to prevent or delay ovulation,” said Dr. Petra M. Casey, an obstetrician-gynecologist at Mayo. “They don’t act after fertilization.”
The F.D.A. declined to discuss decisions about the effect on implantation or to say whether it would consider revising labels. But Erica Jefferson, an F.D.A. spokeswoman, acknowledged: “The emerging data on Plan B suggest that it does not inhibit implantation. Less is known about Ella. However, some data suggest it also does not inhibit implantation.”
Scientists say the pills work up to five days after sex, primarily stalling an egg’s release until sperm can no longer fertilize it. Although many people think sperm and egg unite immediately after sex, sperm need time to position themselves.
Controversy over emergency contraception is figuring in the presidential race and debates over the Obama administration’s health care law. Some abortion opponents and religious groups are fighting the law because it requires insurers, including those for employees of Roman Catholic institutions that oppose birth control, to cover contraceptives, including morning-after pills. While some object to contraception generally, others focus on birth control methods that they believe cause abortions.
And some proponents of “personhood” initiatives, proposals being put forward in several states to define fertilized eggs as people, say the initiatives would bar the pills if they work after eggs are fertilized.
Doctors also say some patients who are not active on abortion issues want to resolve ethical questions about whether the pills affect a fertilized egg.
A Growing Market
While scientific and political disputes over emergency contraception may persist even if labels change, both sides consider the wording on labels central because it summarizes scientific consensus and shapes what medical authorities say.
“F.D.A. labeling is important to us, it’s very important,” said Jeanne Monahan, director of the Center for Human Dignity at the Family Research Council, a conservative group.
Diana Blithe, a biochemist who oversees contraception research for the National Institutes of Health, the federal agency for medical research, said the possibility of an effect on implantation should not be cited on the labels. “As a scientist, I would definitely take it off of emergency contraception,” she said.
Ninety-nine percent of the emergency contraception market in the United States consists of Plan B (approved in 1999 and now sold as Plan B One-Step) and its generic versions, Next Choice and levonorgestrel tablets. They are available without prescription for women ages 17 and older. The other pill, Ella, became available by prescription only in the United States in late 2010. Emergency contraceptive use has steadily increased, with about 12 million packages sold last year, according to IMS Health and the SymphonyIRI Group, health information and market research companies.
European medical authorities have not mentioned an effect on implantation on Ella’s label, and after months of scrutiny, Ella was approved for sale in overwhelmingly Catholic Italy, where laws would have barred it if it could be considered to induce abortion, said Erin Gainer, chief executive of Ella’s manufacturer, Paris-based HRA Pharma.