Morning-After Pills Don’t Cause Abortion, Studies Say
One hypothesis on how Plan B works was by preventing implantation post fertilization - however recent findings show that’s not the case, it works through preventing ovulation.
For years, scientists knew the pills, particularly Plan B, were highly effective in preventing pregnancy after unprotected sex but weren’t exactly sure how they managed that. “It wasn’t really clear whether it worked before ovulation or after ovulation,” says Wood.
Scientists did know the drug worked primarily by preventing ovulation. It stops an egg from being released from a woman’s ovary and thus prevents any chance of fertilization and pregnancy. But they also thought the drug might make it more difficult for a fertilized egg to implant in a woman’s uterus.
Technically, that’s not an abortion, says Wood.
“We know that about half of fertilized eggs never stick around. They just pass out of the woman’s body,” she says. “An abortifacient is something that interrupts an established pregnancy.”
But people like Rudd worry that even if what the drugs do is not technically abortion, it’s still objectionable if it happens after fertilization.
But it turns out, at least when it comes to Plan B, there is now fairly definitive research that shows the only way it works is by preventing ovulation, and therefore, fertilization.
“We’ve learned a lot about how these drugs work,” says Diana Blithe, a biochemist and contraceptive researcher at the National Institute of Child Health and Human Development. “I think it’s time to revise our speculations about how things might work in view of data that show how things do work.”
For example, says Blithe, a study published just last year led the International Federation of Gynecology and Obstetrics to declare that Plan B does not inhibit implantation. And some abortion opponents in the medical community are beginning to accept that conclusion.
“Up until recently I would not prescribe the Plan B product because we didn’t have enough science to say it doesn’t have a post-fertilization effect,” says Rudd. “Now, I’m becoming — sitting on the fence with that.”