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Taking Medication While Pregnant

Safe or Sorry?

Teratogens: The Tests of Time continued...

What scientists have found so far is that only a relatively small number of medications are known teratogens, substances that cause abnormalities in the growing fetus. About one out of every 33 babies is born with birth defects each year; about 2% to 3% of those are believed to be from drug exposure.

"There are very few medications you shouldn't take," says Jennifer Niebyl, MD, head of obstetrics and gynecology at University of Iowa College of Medicine, who has written chapters in medical textbooks on drugs during pregnancy. "Obviously you should check with your healthcare provider first, but if a mother needs medicine for medical illness, she should take it."

The FDA uses the data that's accumulated to classify drugs based on teratogenic risk. There are currently five categories: A, B, C, D and X. Type A drugs are the least harmful, and X have risks that clearly outweigh any benefits. The agency is considering a change to these categories to give doctors and the public a clearer picture of the data available.

In addition to the FDA lists, about 20 teratogen centers throughout the country are constantly updating a database of information on the effects of different drugs in pregnant women. "Having your doctor call and check with a hotline for the most recent information is a really rational thing to do," Filkins advises.

Experts also suggest that pregnant women stick to medicines that have weathered the test of time and avoid those for which there isn't as much data collected, such as some allergy medications recently introduced on the market. Commonly used antihistamines like chlorpheniramine, for instance, haven't been associated with a higher risk of birth defects.

"The Claritins, the Allegras -- the billion-dollar blockbuster drugs you see on TV -- we just don't know much about them. They may be safe during pregnancy; they may not," says Michael Zinaman, MD, a reproductive endocrinologist at Loyola Medical Center in Chicago who counsels patients on drugs to avoid during pregnancy.

Setting the Record Straight

In the 12 years that Filkins headed up the Pregnancy Safety Hotline in Pittsburgh, she was struck by the misinformation and needless fear reflected in many calls. One of the most common was from women who got pregnant while on birth control pills and worried that their babies would be born with VATER association, a series of limb and digestive defects.

"With the doses used today, it's not a very large concern, yet there are so many women who are frightened, and even terminated their pregnancies, because of older reports in the medical literature," Filkins says.

Another common confusion among pregnant women is exposure to X-rays. "There's still much hysteria out there, even though they can be lifesaving and the exposures from diagnostic X-rays rarely approach the 5 rad range at which we begin to have some concern," Filkins says. The risks really aren't suspect until 10 or 20 rads, she says.

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