Hi, Thanks for posting in HCM. I understand your concern. Depo preparation is a contraceptive method for women. It is s made of a hormone similar to progesterone. It is s a shot given in the arm or buttocks and each shot works for up to 12 to 14 weeks. You must take the injection once every 12 weeks if you need to continue contraception and get its full protection. Depo shots starts to work as birth control immediately after the first shot, if you get it within the first 5 days of your menstrual period. It is 99% effective in preventing pregnancy and has a failure rate of 1%. Change in menstrual pattern is the most common side effect. You may have irregular bleeding or spotting. After a year of use, about 50% of women will stop getting their periods. However, periods usually return when they no longer get the shots. You can become pregnant as soon as 3 to 4 months after your last shot. But, sometimes, it up to a year or 2 to conceive after you stop using this type of birth control. It can be assessed by estimating hormone levels like FSH and LH levels in blood and, more so, you should get your periods regularly. Hope the information provided would be helpful. All the best.