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
"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
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
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.