Depo-Provera (Depo) is an injectable form of birth control that is 99.7% effective in preventing pregnancy.
Depo prevents ovulation in some women. It also thickens mucus in the genital tract obstructing the forward movement of sperm and reduces the ability of the uterine lining to be receptive to pregnancy.
Depo is be administered every 12 weeks (or 84 days). If a subsequent Depo dose is not obtained by 91 days, then it will not be administered unless you are on your menses or have abstained from intercourse for two weeks and have a negative pregnancy test. If you are late for your injection, your new injection will not be effective birth control for up to two weeks. The recommended injection site is the buttocks. Common side effects include: irregular bleeding, breast tenderness, bloating, weight gain (5 pounds the first year, 0–3 pounds every year after), acne, headache, worsening depressive symptoms. After the fourth injection, most women do not menstruate anymore. This is not permanent but after discontinuing Depo regular menstruation may not resume for 3-12 months.
Depo effectively prevents pregnancy two weeks after the first injection. Birth control is continuous provided you obtain subsequent injections of Depo when you are due. Depo does not protect you from sexually transmitted infections.
Because Depo decreases your estrogen levels, the drug can also reduce your bone strength. We recommend that you take a daily vitamin and calcium supplement. If you are over 40 years old, Depo may lead to irreversible bone loss. Ask your health care provider about other options for birth control that have no impact on your bone health.