Contragestive is a term used to describe medications or devices that prevent the implantation of a fertilized egg in the uterus, thus preventing pregnancy. This type of birth control is also commonly known as "emergency contraception" or "morning-after pill." There are several synonyms that can be used to refer to contragestives, including post-coital contraception, emergency contraception, and morning-after contraception. Other related terms include non-surgical abortion, hormonal contraception, and intrauterine devices (IUDs). While these terms may describe slightly different methods or types of contraception, they all work to prevent pregnancy by interfering with the fertilization or implantation process.