What is it? A standard pack comes with 21 pills containing estrogen and progestin, and 7 placebo pills (usually called "sugar pills") to take during your period. Now there are pill packs that you take continuously for three-months, resulting in just four periods per year. "There's absolutely no reason for women to have a period if they're using a hormonal birth control," says Elizabeth Micks, M.D., from Oregon Health Sciences University. Typical use of the pill is 91 percent effective, while perfect use (meaning you take it at exactly the same time every day) is 99.7 percent effective.
Pros: Women are less likely to develop significant uterine fibroids when on the pill and it helps to reduce endometriosis as well as the risk of ovarian and uterine cancers, says Dr. Goldstein. Recent studies have done away with the myth that the pill causes weight gain, and it often helps alleviate acne.
Cons: Smokers and people with high blood pressure should not take the pill because of the risk of increased blood pressure. Because the pill is most effective when taken at the same time each day, forgetting to take it regularly lowers your protection against pregnancy.