Mirena

Mirena is a small, implantable device that your gynecologist will insert into your body at the office. Placing the device takes just a few minutes and doesn't involve any surgery. Once in your body, Mirena releases small amounts of levonorgestrel, a progestin hormone that thins your uterine lining and thickens your cervical mucus, both of which prevent sperm from fertilizing the egg.

As long as Mirena stays in place, it is 99 percent effective at preventing pregnancy for up to five years. After that, you'll need to get a replacement IUD to avoid getting pregnant. If you do have Mirena removed, consider using another form of birth control from our wide array of selections immediately, as you will no longer have protection against pregnancy.

Mirena does not suppress ovulation, but because it does thin out the lining of your uterine wall, it means your periods won't be as heavy as usual. When you first get Mirena, you may find your periods become irregular and heavier at first. However, as your body adjusts, your periods should get lighter and less frequent. Some women don't have any periods at all while on Mirena.

Luckily, Mirena does not cause weight gain in most women. However, like all forms of birth control, there are a few other side effects to watch out for. Though unlikely, these effects include pain or dizziness after placement, ovarian cysts, and irregular periods.