Progestin injections are shots of a type of progestin that is given to women for birth control. Medroxyprogesterone acetate (i.e., Depo-Provera) is the progestin used in these shots. It is similar to the female hormone progesterone that the body naturally produces.
Progestin injections are often used as birth control, to prevent pregnancy. They are also used to control heavy or irregular menstrual bleeding. Progestin injections also decrease a woman's risk for uterine cancer.
Progestin injections prevent pregnancy in these ways: They inhibit ovulation, or the release of an egg from the ovaries.They thicken vaginal secretions to prevent sperm from traveling through the uterus to fertilize an egg.It may possibly change the lining in the uterus to prevent a fertilized egg from implanting.
Progestin injections are generally given in the muscle of the buttocks or upper arm. A single injection provides birth control for 12-13 weeks. It can be repeated if the woman wishes to continue birth control.
It is very important for a woman to get these shots exactly every 12 or 13 weeks, depending on the formulation of the shot. The shots are less effective in preventing pregnancy if the time between shots is more than 12-13 weeks. Injections may be given more often if they are used for heavy or abnormal menstrual bleeding.