Modern oral contraceptive pills are safe for the majority of American women. The most important contraindications to oral contraceptive pill use are a history of thrombophlebitis or thromboembolism while on the pill or during pregnancy, smoking over 15 cigarettes daily if over 35 years of age, active liver disease, hypertension, diabetes, a lipid disorder, or breast cancer. A history of gestational diabetes is not an absolute contraindication to oral contraceptive pill use, but women with such a history must be encouraged to exercise and eat properly to reduce the high risk of developing overt diabetes. Couples should be encouraged to use condoms to reduce the risk of sexually transmitted diseases. Most antibiotics do not decrease the effectiveness of the pill. Nonuse of contraception among adolescents and older couples is the most common reason for failure. Postcoital contraceptive pills are available but are not completely effective. The use of modern contraceptives is almost always safer than nonuse.