GIDEON KOREN, M.D., ANNE PASTUSZAK, M.SC., AND SHINYA ITO ,M.D.
Before marketing a new drug, the manufacturer almost never tests the product in pregnant women to determine its effects on the fetus. Consequently, most drugs are not labeled for use during pregnancy. Typically, descriptions of drugs that appear in the Physicians’ Desk Reference and similar sources contain statements such as, “Use in pregnancy is not recommended unless the potential benefits justify the potential risks to the fetus.” Since the risk has been adequately established for only a few drugs, physicians caring for pregnant women have very little information to help them decide whether the potential benefits to the mother outweigh the risks to the fetus. These typical disclaimers,although understandable from the medicolegal standpoint, put large numbers of women and their physicians in difficult situations for several reasons. One is that at least half the pregnancies in North America are unplanned,and every year, hundreds of thousands of women therefore expose their fetuses to drugs before they know they are pregnant. Such women often interpret the statement that use during pregnancy is not recommended as meaning that the drug is not safe during pregnancy. There is evidence that this perception of fetal risk causes many women to consider or even seek termination of otherwise wanted pregnancies. Another reason is that with the recent increase in the age at which women have children, conditions that necessitate long-term drug therapy are diagnosed in larger numbers of women Bbefore pregnancy. Furthermore, for pregnant women with certain conditions once believed to be incompatible with pregnancy, such as systemic lupus erythematosus and heart diseases, the outcome of pregnancy has improved dramatically in the past few decades.
In this article, we review current knowledge of the fetal and neonatal effects of prescription and over-the-counter drugs given to pregnant women, with an emphasis on the approaches used to determine safety and risk. In addition, we review approaches to communicating such information to pregnant women and their families.
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