Feb. 15, 2001 -- For women who are pregnant, especially those in their first trimester, it seems there are about a zillion medications that are off-limits. Check the back of even the most benign over-the-counter remedy and you will find the familiar warning that pregnant women should "seek the advise of a professional before using this product."
But several new studies suggest that women who are expecting don't have to worry about medications containing the over-the-counter cough suppressant dextromethorphan. Researchers found no increase in birth defects among women who had used the suppressant during pregnancy, contradicting a widely publicized study from three years ago involving chick embryos.
"Dextromethorphan has been on the market for many, many years, and until this embryo study was published, it was considered perfectly safe during pregnancy," Adrienne Einarson, RN, of Ontario's Hospital for Sick Children, tells WebMD. "There was absolutely no evidence in humans to suggest this drug was harmful, but suddenly it was considered dangerous on the basis of this one animal study."
Einarson and her colleagues run Motherisk, a Canadian-based program designed to counsel pregnant women and their health providers regarding exposures to drugs and environmental agents. They decided to study dextromethorphan, Einarson says, after receiving calls to their hotline asking about its safety.
Just under 200 women who had called the hotline and later reported using the cough suppressant during pregnancy (most in their first trimester) were included in the study, as were a similar number of women who had asked about the safety of dextromethorphan but did not take it during pregnancy. All the women were contacted after giving birth, and the researchers found no significant difference between the two groups in the incidence of birth defects. Both were in the usual range of 1% to 3%. The findings were reported in the February issue of the journal Chest.
A separate study, published in the January issue of the journal Teratology, also came to the same conclusion but had a different design. In that study, women who had babies with birth defects were compared to women who had babies without apparent birth defects.
"I think these studies complement each other quite well, and the message is that there does not seem to be any harm in taking cough medicines containing dextromethorphan," Einarson says. "When we counsel pregnant women, we tell them to try and put the risks and benefits into perspective with this or any drug. There are certainly drugs that do cause birth defects, but there are also many drugs that are really quite safe to use during pregnancy. The idea that women should never take any drugs during pregnancy is rather dangerous."
While agreeing that many drugs may be safe to use during the critical first few months of pregnancy, Texas ob-gyn Norman F. Gant, MD, says it is still prudent to take a conservative approach to medications during this time. Doctors know little about how certain drugs affect growing fetuses, he says, because it is not ethically possible to conduct the kinds of studies that will answer these questions. Gant is a professor of obstetrics and gynecology at the University of Texas Southwestern Medical School in Dallas, and executive director of the American Board of Obstetrics and Gynecology.
"It is true that obstetricians and gynecologists tend to be overcautious," he tells WebMD. "We want to do everything we can to ensure that during the first trimester, a birth defect doesn't occur. It is just better during that time to try not to take any drugs, and certainly abstain from alcohol and cigarettes."
University of California at Los Angeles ob-gyn and geneticist Karen Filkins says the most important thing a woman can do to protect against drug-related or environmental-related birth defects is to examine potential exposures prior to becoming pregnant.
"If a woman is planning a pregnancy, she should look at all possible exposures -- everything she is putting in her mouth, potential occupational exposures, and other environmental exposures. And if she has questions, she should ask her ob-gyn. Then she can alter whatever has to be altered."