It is a hormone much like the progesterone a woman produces during the last 2 weeks of each monthly cycle. It stops the woman from ovulating and thickens cervical mucous. Among typical couples who initiate use of Depo-Provera, about 3 in 1000 will experience an accidental pregnancy in the first year.
Contraception is immediate if the shot is given in the first five days of the menstrual cycle.
Complete information about this contraceptive is available through your clinician or through the package insert accompanying Depo-Provera injections. Most clinics provide the first shot when a woman is on her period or within 7 days of the start of the period. Be sure to use condoms or another method until your provider tells you that your next shot may be considered effective. Nothing needs to be taken daily or at the time of sexual intercourse. Women lose less blood using Depo-Provera and have less menstrual cramps.