Why it's done

Combination birth control pills are a reliable form of contraception that's easily reversed. Fertility can return to normal almost immediately after stopping the pills. Other, noncontraceptive benefits of these pills include:

• Decreased risk of ovarian and endometrial cancers, ectopic pregnancy, ovarian cysts, benign breast disease
• Improvement in acne
• Less-severe menstrual cramps (dysmenorrhea)
• Reduction in androgen production caused by polycystic ovary syndrome
• Reduction in heavy menstrual bleeding due to uterine fibroids and other causes, as well as a reduction in related iron iron-deficiency anemia
• Relief from premenstrual syndrome (PMS)
• Shorter, lighter and more-predictable periods or, for some types of combination pills, fewer periods yearly
• Better control of monthly cycle and a reduction in hot flashes for women nearing menopause (perimenopause)

Combination birth control pills come in different mixtures of active and inactive pills, including:

• Conventional pack. The most common type contains 21 active pills and seven inactive pills. Formulations containing 24 active pills and four inactive pills, known as a shortened pill-free interval, also are available.

  You take a pill every day and start a new pack when you finish the old one (every 28 days). Bleeding occurs every month during the week when you take the last four to seven inactive pills.

• Continuous dosing or extended cycle. These typically contain 84 active pills and seven inactive pills. Bleeding generally occurs only four times a year during the seven days you take the inactive pills.

  A 365-day pill also is available. You take this pill every day at the same time. For some women, periods stop altogether. For others, periods become significantly lighter.

Continuous-dosing and extended-cycle pills might provide additional benefits of suppressing menstruation, such as:

• Prevention and treatment of excessive bleeding related to uterine fibroids
• Prevention of menstrual migraines
• Reduction in menstruation-associated worsening of certain conditions, including seizures
• Relief from pain related to endometriosis

Combination birth control pills aren't appropriate for everyone, however. Your health care provider might suggest you take another form of birth control if you:

• Are in the first month of breast-feeding
• Are older than 35 and smoke
• Have poorly controlled high blood pressure
• Have a history of or current deep vein thrombosis or pulmonary embolism
• Have a history of stroke or heart disease
• Have a history of breast cancer
• Have migraines with aura
• Have diabetes-related complications, such as nephropathy, retinopathy or neuropathy
• Have liver disease
• Have unexplained uterine bleeding
• Will be immobilized for a prolonged period due to major surgery