Got a New Rx? How Will It Affect a Future Pregnancy?

The next time you're prescribed a medication, ask your doctor what would happen if you became pregnant while taking it.

If you're thinking of conceiving soon, pay attention to this: Nearly half of young women who are prescribed potentially birth defect-causing drugs receive these medications without being told to avoid getting pregnant, according to a new study of nearly 500,000 15- to 44-year-olds published in the Annals of Internal Medicine.

Why it matters: Because half of all pregnancies in the U.S. are actually unplanned. So you could be taking these medications -- which include certain common acne medications, antibiotics, cholesterol reducers, sleep meds. and anti-anxiety drugs -- in the early stages of pregnancy, when growing fetuses are most vulnerable to birth defects because their vital organs are forming.

"Women receive millions of prescriptions for these medications a year, and up to six percent of pregnancies are exposed to them unwittingly," says study author Eleanor Schwarz, MD, an assistant professor of medicine, obstetrics, gynecology, and reproductive sciences at the University of Pittsburgh Medical Center.

The message here is not to stop taking these important and sometimes life-saving drugs, says Schwarz. "But you may simply need a more reliable form of birth control -- to prevent unplanned pregnancies -- when you're using one of these medications." Condoms and diaphragms are significantly less effective than hormonal methods like birth control pills or vaginal rings, for example. (IUDs, which are the most effective contraceptive available, offer another very safe option for women not planning to get pregnant in the next five years.)

Don't wait for your doctor to jump-start this conversation, says Schwarz. "Our research shows that it's important for patients to be proactive. Whenever you're prescribed a new medication, ask your doctor, 'Would this cause a problem if I were to become pregnant?'" she says. "This opens the door for a chat about protection and whether you have the best type of birth control for your current needs."