Best if: You're breastfeeding; You don't want to get pregnant tomorrow
How it works: You get a shot of progestin in your butt or arm once every three months; you or your doctor can do it.
Perks: You only have to deal with it four times a year.
Drawbacks: Depo-Provera isn't a popular choice for several reasons: It can cause heavy break-through bleeding and weight gain, and may even increase your risk of osteoporosis if you use it for more than two years.
Fertility returns 9 to 12 months after your last shot.