Depo-Provera is a highly effective, hormonal birth control method that contains progestin. It does not contain any estrogen. It is given by injection (a needle) every 12 weeks (3 months) to prevent pregnancy.
How does it work?
An injection is given in the arm or buttocks 4 times per year (every 12-13 weeks), by a health professional. The hormone progestin works to prevent pregnancy in 3 ways:
Stops the ovaries from releasing an egg each month
Thickens the cervical mucus making it difficult for sperm to get through
Changes the lining of the uterus making implantation difficult
How effective is it?
It is 99.7% effective in preventing pregnancy if the shot is given on time every 12 weeks. With typical use, it is 97% effective.
What are the advantages?
One of the most effective birth control methods available
Does not contain estrogen
Only need to think about it 4 times per year (one injection lasts for 3 months)
Effectiveness is not reduced by other common medications
May be suitable for breastfeeding women or women who smoke
Can reduce menstrual cramps
May stop having periods (amenorrhea). After 1 year over 50% will stop having periods, and after 2 years over 66% will stop having periods. This is not unhealthy.
Improves symptoms of endometriosis
Decreases the risk of endometrial cancer
Effective within 24 hours when given during the first 5 days of a normal menstrual period
Other side effects of progestin include: weight gain, decrease in bone mineral density and delayed return of fertility
Bone density loss is of particular concern for teenage girls whose bones are still growing and hardening. Women using Depo-Provera should make sure that they get enough calcium and vitamin D in order to help protect their bones.
Return of fertility is longer than with oral contraceptive users. It takes an average of 9 months after the last injection for the ovaries to start releasing eggs again.
Women must return to their health care provider every 12 weeks to receive their next injection