Not necessarily. The main thing to avoid is contraceptives that contain estrogen, which can reduce your milk supply. So women who are exclusively breastfeeding need to steer clear of birth-control pills that contain both estrogen and progestin, as well as the Patch (a bandagelike square that delivers hormones into your bloodstream) and the Ring (which you insert into your vagina, where it releases hormones).

Instead, you could use a "mini-Pill" -- a progestin-only contraceptive, such as Micronor, that won't affect milk supply. (One caveat: It's important to take the mini-Pill at the same time every day for optimal effectiveness.)

You can also safely use an intrauterine contraceptive (IUC) or try any barrier method, such as a diaphragm, cervical cap, sponge, condom, and Leah's Shield (a reusable rubber insert), says Karen Meckstroth, M.D., assistant clinical professor of obstetrics and gynecology at the University of California, San Francisco.

I'm not sure whether I'm done having babies, so what's long-term but not permanent?

An IUC is ideal, and there are two types. The first, the Mirena IUC, releases a steady stream of progestin and is the most popular birth control with female ob-gyns.

It's even more effective than tubal ligation if it stays in place, says Dr. Meckstroth. It most likely works by changing the texture of cervical mucus so that it blocks sperm from reaching the eggs. It can also prevent ovulation. It's approved for up to five years, and once it's removed you can get pregnant right away.

There's also ParaGard, an IUC that's approved for up to ten years and doesn't use hormones. It releases copper instead, which experts think creates an environment that's toxic to sperm. It may also keep the egg from attaching to the uterus.

Another option: Implanon, a matchstick-size rod that's implanted under the skin of your arm to release progestin and lasts for up to three years. One downside: It often causes breakthrough bleeding, so you'd have to be willing to put up with that.