Most common types of contraception — birth control pills, condoms, hormonal intrauterine devices and implants — prevent conception by keeping eggs from becoming fertilized.
The description “abortion-inducing” is most often used by anti-abortion religious groups to characterize methods they believe can prevent a fertilized egg from implanting in the uterus. These groups typically say that such methods are morning-after pills and copper intrauterine devices.
There are two main reasons this belief does not comport with scientific evidence. First, the medical definition of pregnancy is that it begins after a fertilized egg is implanted in the uterus, not before. That is because many, probably most, fertilized eggs naturally fail to implant in the uterus on their own.
Second, a growing body of research strongly indicates that morning-after pills, such as Plan B and Ella, do not prevent implantation. Instead, the pills, if taken up to five days after unprotected sex, work to stop fertilization from occurring. They do this by delaying ovulation, the release of eggs from the ovaries that occurs before eggs are fertilized, or by thickening cervical mucus so that sperm have trouble swimming and reaching the egg to fertilize it.
A New York Times investigation of the science behind morning-after pills in 2012 prompted the National Institutes of Health website to delete passages suggesting emergency contraceptive pills could disrupt implantation. A spokeswoman for the Food and Drug Administration said at the time that “emerging data” suggested that morning-after pills do not inhibit implantation.