Anonymous wrote:Emergency contraceptive pills do not have an impact on implantation! They all work to prevent ovulation, which prevents fertilization. A fertilized egg can still implant if you've taken the morning-after pill. Ella is the best one, but the only one that requires a prescription. A copper IUD (Paragard) has been shown to be the best emergency contraception option because it makes the uterus very inhospitable to sperm, and it *may* prevent implantation, but that hasn't been definitively proven.
The FDA says it may in fact prevent implantation:
"Plan B works like other birth control pills to prevent pregnancy. Plan B acts primarily by stopping the release of an egg from the ovary (ovulation). It may prevent the union of sperm and egg (fertilization). If fertilization does occur, Plan B may prevent a fertilized egg from attaching to the womb (implantation). If a fertilized egg is implanted prior to taking Plan B, Plan B will not work."
https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/fdas-decision-regarding-plan-b-questions-and-answers