PHILADELPHIA – Doctors aren't doing a very good job of warning young women to avoid getting pregnant when they're taking prescription drugs that can cause birth defects, a new study suggests.
Nearly half of the women taking the medicines didn't get counseling from their doctor about using contraceptives or other birth control measures, University of Pittsburgh Medical Center researchers found in a study of nearly 500,000 women.
"The message is not that women should avoid taking prescription medications that they need and that their doctors recommend," said Dr. Eleanor Bimla Schwarz, lead author of the study in Tuesday's Annals of Internal Medicine.
But women should discuss the potential pregnancy risks with their doctors before taking the drugs, she said.
The researchers noted that the study might overestimate the problem because the data is from health plan billing codes, which don't have the same detailed medical histories as patient medical charts. Some doctors may have provided counseling but didn't bother to mark it with a billing code.
Even with its limitations, they say, it's clear that lots of women aren't getting the message about avoiding pregnancy while taking certain drugs. Medicines that may cause birth defects include some antibiotics, acne medications, cholesterol reducers, anti-seizure drugs, sleep aids and blood thinners.
The researchers looked at data for women ages 15 to 44 enrolled in Kaiser Permanente Northern California in 2001 who filled about 1 million prescriptions. One in six of the women got at least one prescription for a drug with birth-defect risks.
They found that women prescribed drugs that might cause birth defects were no more likely to get counseling about pregnancy prevention than women prescribed safer drugs. Of women in the high-risk drugs group, 48 percent got no guidance from their doctors; in the safe drugs group, 47 percent got no guidance.
The severity of the problem might not be as bad as the study suggests, but it's clear there is a problem that demands more vigilance by doctors and patients alike, said Dr. Michael Katz, acting medical director for the March of Dimes.
"One of the things this paper does is raise consciousness and that's very helpful," he said.
The researchers found that internists and family doctors prescribed the highest proportion — 48 percent — of the riskier drugs to women of childbearing age, with psychiatrists, dermatologists and obstetricians-gynecologists far behind.
The Food and Drug Administration classifies drugs into categories of whether they're safe or potentially harmful to developing fetuses. But the reality for busy doctors often means they don't consult the FDA listings, Schwarz said.
Researchers generally didn't see big differences in counseling depending on the type of high-risk drug. But they did find that women on the acne drug isotretinoin, best known by the brand name Accutane, got more pregnancy prevention counseling than anyone else. Women taking statins for cholesterol got the least counseling.
Anyone taking Accutane or one of its generic competitors is required to use birth control, pass a pregnancy test before each monthly refill and enroll in a national registry. Despite that program, administrators in July reported that more than 120 women became pregnant in the previous year.
The Pittsburgh study was partly funded by Duramed, a subsidiary of generic drug maker Barr Pharmaceuticals Inc.