Birth control pills (BCPs) are extremely effective at preventing pregnancy if used correctly and consistently. For example, only five in 1,000 women is likely to get pregnant in the first year of use.

The pill works mainly by preventing ovulation or by thickening the mucus surrounding the cervix, which helps block sperm, reduces risk of symptomatic pelvic inflammatory disease, and thin the lining of the uterus so if an egg is fertilized, it would have trouble implanting.

The pill is the most common form of reversible birth control used by women ages 15 to 44. More than 27 million women in the U.S. are currently using BCPs.

According to the National Cancer Institute, the most serious side effect of the pill continues to be an increased risk of cardiovascular disease. This risk is particularly high in certain groups, like women who smoke who are over 35.

You may not know it, but the pill can help your health. For example, birth control pills can improve menstrual problems like heavy bleeding, pelvic cramps and pain, premenstrual syndrome and irregular cycles. They can prevent loss of bone density and reduce the risk of ovarian cysts. Pill use can also protect you from uterine and ovarian cancer.

The Women's Contraceptive and Reproductive Experience (Women's CARE) study indicated that present or past use among both Caucasian and African-American women ages 36 to 64 did not significantly increase the risk of breast cancer.