Not only Yaz is a birth control pill to prevent pregnancy, but also it has quite a few medical benefits. Many teen girls take the birth control pills just for its medical benefits and not for its protection against pregnancy. Irregular Menstrual Periods: For girls whose menstrual periods are irregular (too often or too late) birth control pills can help to regulate the menstrual cycle. Birth control pills also can reduce the amount and length of menstrual bleeding. Acne: Birth control pills also improve acne. For moderate to severe acne, which over-the-counter and prescription medications can't cure, birth control pills may be prescribed. The hormones in the birth control pill can help stop acne from forming. It doesn't usually matter which type of birth control pills you take, since most of them can be used to treat acne. Be patient though, since it takes several months for the birth control pills to work. Other Medical Benefits: because there is less menstrual bleeding with the use of birth control pills, you are less likely to get anemia Birth control pills decrease your chance of getting endometrial cancer and ovarian cancer, ovarian cysts, and breast lumps. The birth control pill also protects against infections of your fallopian tubes that would need hospitalization. It also protects against pregnancies that occur outside the uterus.