A woman's choice – Women have many choices when it comes to avoiding pregnancy. According to the Centers for Disease Control and Prevention, 99% of sexually active women from 2006 to 2010 used at least one contraceptive method at some point. Here's a look at a variety of birth control methods and how they each work.
IUD – An intrauterine device, or IUD, is a flexible T-shaped device that's inserted by a doctor into a woman's uterus. The devices block sperm and change the lining of the uterus, which may keep a fertilized egg from attaching. Pregnancy is prevented from three to 12 years, depending on the type.
The pill – Approved in 1960 by the Food and Drug Administration, oral contraceptives involve taking a daily pill with a combination of estrogen and a progestin. The hormones prevent ovulation and thicken a woman's cervical mucus, blocking sperm from fertilizing an egg.
Female condom – Condoms aren't just for men. The female condom fits inside the vagina with a ring at one end that covers the cervix. When used correctly all of the time, the National Institutes of Health says, it's 95% effective, with bonus protection from sexually transmitted infections.
Diaphragm – The diaphragm also fits inside the vagina but covers only the cervix, where it blocks sperm from entering the uterus. It is made of silicone and can last up to two years. A spermicide must also be used for greatest effectiveness.
Cervical cap – The cervical cap is similar to a diaphragm but smaller in size and made of rubber instead of silicone. It is useful for women who find it hard to keep a diaphragm in place.
Implant – Implants are flexible matchstick-size devices that are surgically inserted into a woman's arm. They slowly release the hormone progestin into the body, preventing a woman's ovaries from releasing eggs. The protection can last several years.
The patch – For women who don't want to take a pill or insert a device, the Ortho Evra birth control patch sticks to the body and releases pregnancy-preventing hormones through the skin. A woman must change her patch once a week for three weeks in a row. No patch is used in the fourth week, and then the cycle starts again.
Vaginal ring – NuvaRing, approved for use in the United States in 2001, is a small, flexible ring inserted into the vagina. It releases estrogen and progestin, the same pregnancy-preventing hormones found in most variations of the birth-control pill.
Vaginal sponge – Introduced in 1983, the Today Sponge was pulled from the market after fears of toxic shock but returned in 2005 following design changes. The sponge contains spermicide and can be inserted into the vagina before sex, like a diaphragm, to prevent pregnancy.
The shot – Depo-Provera, an injection form of birth control, provides protection for three months with hormones that prevent ovulation and block sperm. It doesn't contain estrogen, as do some other forms of birth control. As a result, it is a popular option for women who can't take estrogen or who are breastfeeding.
Morning-after pill – Emergency contraception, frequently referred to as the morning-after pill, can be taken to prevent pregnancy up to five days after unprotected sex. It can prevent the ovaries from releasing eggs and thickens a woman's cervical mucus. The morning-after pill can also thin the uterus lining, which could prevent a fertilized egg from attaching.