Medication Use by Pregnant Women Climbs

Pregnant women today know that using tobacco and drinking alcohol is risky to their fetus, and a majority of them avoid these substances. But researchers at BU’s Slone Epidemiology Center have found that an increasing number of pregnant women are taking both over-the-counter and prescription drugs. Their study, recently published in the American Journal of Obstetrics and Gynecology, also found that medication use varied considerably by women’s socioeconomic status, age, ethnicity, and where they lived.

Although some drugs are known to increase the risk of birth defects, the study, done in collaboration with the federal Centers for Disease Control and Prevention (CDC) and the Harvard School of Public Health, strongly suggests that far more information is needed on the risks and safety of the vast majority of commonly used medications, both prescription and over-the-counter (OTC), says Slone Center director and study lead investigator Allen Mitchell, a School of Public Health professor of epidemiology and a School of Medicine professor of pediatrics. Because of the number of medications being used and the lack of sufficient safety information for so many of them, the study raises concerns that pregnant women may unknowingly take a medication that could pose a risk to the fetus, Mitchell says, and at the same that they might be discouraged from taking medically useful medications that might be relatively safe.

With two bodies of data gathered by Slone researchers (the Slone Birth Defects Study database has more than 40,000 mother-child pairs) between 1976 and 2008, and by the CDC’s National Birth Defects Prevention Study between 1997 and 2003, the researchers analyzed interviews of 32,700 women who gave birth, to both infants with birth defects and infants without birth defects, and identified their use of medications during pregnancy. “While drug-related birth defects are rare,” says Mitchell, “fears of danger to the fetus, usually based on there being too little information on their effects, may lead pregnant women to avoid some medicines, such as influenza vaccines and asthma medications. However, we know that both these medicines can have very important health benefits to both the mother and her unborn infant, and the study underscores the need for women to know which drugs are relatively safe and which are not.

“Our report doesn’t conclude that women should stop using medicines or cut back,” he says. “We’re saying women and their health care providers should have all the information they need to balance the benefits of taking a medication against its possible risks.”

The Slone study found that by 2008, nearly half the women interviewed reported taking at least one prescription medication during their first trimester, a 60 percent increase over the first years of the study, and 70 to 80 percent recalled taking over-the-counter medications. In the 35 years since the study began, the use of four or more medications during the first trimester tripled, an increase attributable in part to the dramatic rise of so-called SSRI (selective serotonin reuptake inhibitor) antidepressants such as Prozac. In their in-depth interviews of women after they’d given birth, the researchers also found that medication use increased with a woman’s age and education level, and use of medications was more prevalent among non-Hispanic white women than among women of other races or ethnicities.

Older Americans may remember the horrifying birth defects—mainly malformed limbs resembling flippers—that resulted from pregnant women taking the sedative thalidomide to ease the nausea associated with morning sickness. The Food and Drug Administration (FDA) never approved the drug for use in pregnant women, but its widely publicized effects in Europe sent a collective chill down Americans’ spines. “We know from thalidomide that drugs can do devastating things to the fetus,” says Mitchell, “and you might think that the collective memory would raise caution about taking drugs during pregnancy. But the collective memory is very short.”

Thalidomide is still prescribed today, primarily to treat multiple myeloma, a rare form of cancer. Since even a single dose of thalidomide taken during pregnancy can cause severe birth defects or the death of an unborn baby, a program called System for Thalidomide Education and Prescribing Safety (S.T.E.P.S.®) has been approved by the FDA to make sure pregnant women do not take the drug and women taking it do not become pregnant. All people who are prescribed thalidomide, including women who cannot become pregnant and men, must be registered with S.T.E.P.S.®

But for pregnant women, the benefits of some drugs may far outweigh risk, resulting, for example, in a push by physicians for them to be vaccinated against the flu and for those who need asthma medications and antidepressants to remain on them throughout pregnancy. Aggressive treatment with these drugs is important. When it comes to asthma, “we know it’s not good for the pregnant woman or her fetus to be oxygen-deprived,” says Mitchell. “What we need to do is study what risks, if any, might be involved—in other words, the whole picture.”

According to the National Research Council, 3 percent of all birth defects and developmental disabilities are caused by environmental exposures and another 25 percent or more may be caused by an interaction between genes and the environment. Still, the broadening use of OTC and prescription medicines during pregnancy deserves rigorous study, Mitchell says. In the case of antidepressants, he believes that further study will underscore the safety of the majority of these relatively new treatments. “Antidepressants may be a good example of doctors and their pregnant patients overreacting to the risk side of the equation,” he says. Depressed pregnant women have an increased risk of delivering low–birth weight babies, a higher risk of postpartum depression, and an often-impaired ability to bond with their new babies. So far, the risks that have been identified with certain antidepressant medications are rare, and doctors and their patients need to be careful to keep this in mind when deciding about treatment choices.

OTC drugs that should be avoided during pregnancy include aspirin and some laxatives, according to Consumer Reports Health. Others, like antihistamines, ibuprofen, and stomach remedies such as Pepto-Bismol should be used with caution early in pregnancy and avoided during the third trimester.

But these risks are minute compared with the tragedy of thalidomide. Mitchell attributes the study’s results to several factors. First, “we’re seeing a lot of over-the-counter medications that are being heavily promoted, and a lot of prescription drugs being switched to over-the-counter,” in particular the profusion of cold, flu, and pain medications. “We’re also seeing treatment for medical conditions, such as depression, that weren’t frequently treated years ago.”

“We’re not taking a position on whether women should or shouldn’t take medicines; rather, because the kinds of medications used in pregnancy change over time, we’re saying that we need to focus the most research attention on the medicines that pregnant women are taking now,” he says, “and we need to learn as much about their possible risks and safety as we can.”

Susan Seligson can be reached at sueselig@bu.edu.