Implant A small rod, about the size of a matchstick, that prevents pregnancy for up to 4 years. A doctor or nurse inserts the implant under the skin of the upper arm. It releases the hormone progestin to prevent pregnancy. Related Articles: Glossary: EndometriumGlossary: Implanon20 Types of Birth Control, Debunked Myths & Other Uses For Contraceptives: A Resourcedoin' it, or not Implanon Implantation
