Birth-control options such as the Pill use synthetic versions of your body's reproductive hormones to prevent ovulation, the release of an egg needed for a successful pregnancy. While some contain both estrogen and progestin, breastfeeding moms should choose one that only contains progestin, as estrogen can make it more difficult to produce enough breast milk. Progestin-only choices may decrease menstrual cramping and lower your risk of pelvic infection, but a few women will experience nausea, headaches, or irregular bleeding.
* Minipills, an oral contraceptive, are 94 to 96 percent effective when taken at the same time every day.
* Depo-Provera, an injection administered by a doctor or nurse, protects for three months at a time and is 99.7 percent effective. Note that the return of fertility may be delayed for three months after stopping it.
* Mirena is an intrauterine contraceptive that can be inserted right after delivery and lasts for five years. It is 99.9 percent effective and has the lowest hormonal dose available.
* Implanon, to be available in 2004, is a single, flexible, plastic implant placed under the skin. It releases a low hormone dose and is 99.9 percent effective for up to three years.
These are hormone-free options that offer protection from sexually transmitted diseases. These choices are slightly less effective, but with the added protection that breastfeeding offers, they almost always prevent pregnancy if used properly.
* A diaphragm is a rubber disk used with spermicide to cover the opening of the uterus; it's 80 percent effective. It can't be fitted to a woman's cervix until about six weeks after delivery. (If you were using one before pregnancy, your doctor will need to refit you.)
* A cervical cap is a rubber thimble-like device used with spermicide that suctions onto the cervix; it has a 60 to 80 percent effectiveness. (The above fitting guidelines also apply.)
* Condoms are a convenient and inexpensive option that are 86 percent effective.