Maternal use of prescribed drugs associated with recognized fetal adverse drug reactions.

To quantitate the frequency of exposure in pregnancy to selected drugs listed by the American Medical Association's Department of Drugs as having known or suspected association with fetal adverse drug reactions, we examined the prescription records of 18,886 Michigan Medicaid recipients who delivered a liveborn infant between April 1, 1981, and March 31, 1983. Focusing only on specific trimesters considered risk periods for each drug-fetal occurrence of adverse drug reaction, the use of tetracyclines during the first trimester of pregnancy was the most prevalent (21.3 exposed women/1000) prescribed drug associated with known or suspected fetal adverse drug reactions. The second most prevalent was phenobarbital in the first trimester, with 10.8 women exposed/1000. Following a close third was the use of the sulfonamides in the second trimester, with 10.0 women exposed/1000. The prescribing of nitrofurantoin and the sulfonamides in the last trimester and tetracyclines throughout pregnancy appears excessive. There are few indications for the outpatient use of the tetracyclines during pregnancy. Practitioners caring for pregnant women need to carefully evaluate the need for these drugs and consider when risks may outweigh benefits.