Some drugs can cause birth defects and other problems if a woman takes them while pregnant. The U.S. Food and Drug Administration classifies drugs according to safety during pregnancy. Drugs in classes A and B are safe, whereas drugs in classes D and X are potentially unsafe. Women who receive prescriptions for class D and X drugs should also receive counseling about birth control if they could become pregnant (that is, if they are sexually active with men, have not yet gone through menopause, and have not had a hysterectomy or had their tubes tied). Appropriate birth control services include counseling to avoid sexual activity until after they have stopped taking the drug, prescription of birth control drugs or devices, or regular use of condoms or other nonmedical forms of birth control.