Medication use during pregnancy

Evaluating risk is an ongoing challenge Medication use during pregnancy is remarkably common. In the linked paper in this issue (doi:10.1136/bmj.g5159), Bech and colleagues assess the risk of spontaneous abortion and stillbirth after antiepileptic drug use during pregnancy, utilizing national health registers in Denmark from 1997 to 2008.1 The findings are largely reassuring, but studying the effects of drug use in pregnancy is always a challenge and confident conclusions about safety are rarely possible. Estimates of prescription drug use including vitamins and minerals during the first trimester have ranged from 33% to 69% in developed countries.2 The average number of over the counter and prescription drugs used by pregnant women in the United States increased from 2.5 in 1976-78 to 4.2 in 2006-08.3 And yet the quantity and quality of information about the risk to the fetus of medication use during pregnancy remains poor. A review of 172 medications approved by the US Food and Drug Administration between 2000 and 2010 found that for 97.7% the teratogenic risk in human pregnancy was undetermined; for 73.3% there were no available data about the risk in pregnancy.4 However, because many pregnancies occur unintentionally, women who take medications can be exposed in …