What is an injectable form of birth control?

The injectable hormone progestin is a reversible and effective method of contraception. Either your doctor or a nurse will administer the injection in the muscle of your upper arm, buttocks or thigh. The injection lasts for 10 to 13 weeks (approximately 3 months) after which time you must have another injection to maintain the contraceptive benefits.

How does it work?

Progestin interferes with the natural cycle, but unlike oral contraceptives cannot profoundly suppress it. It stops ovulation and acts on the lining of the uterus walls - and on the jelly like mucus at the entrance of the cervix, to make it difficult for sperm to get through.

How effective is it?

Injection contraception can be quite effective. It is the second most effective reversible form of contraception. The method is fully effective 24 hours after injection. The failure rate for women who use this form of birth control is about 3 pregnancies in 1000 women who use this form of contraception for one year.

Are there side effects?

Possible weight gain and irregular bleeding.

What are the benefits?

• injectable progestin can be used by women who cannot take estrogen
• no need to remember to take pill everyday
• provides contraception for up to 3 months
• highly effective at preventing pregnancy

Drawbacks?

• you must make regularly scheduled appointments for renewed injections
• if you are planning to become pregnant, it will take several months before you start to ovulate and resume normal menstrual cycles