BACKGROUND:There are few data regarding the utilization of opioids during pregnancy. The objective of this study was to define the prevalence and patterns of opioid use in a large cohort of pregnant women who were commercial insurance beneficiaries. METHODS:Data for the study were derived from a deidentified research database of women from across the United States who had both medical and prescription benefits. By using diagnostic codes, the authors defined a cohort of 534,500 women with completed pregnancies who were enrolled in a commercial insurance plan from 6 months before pregnancy through delivery. RESULTS:Overall, 76,742 women (14.4%) were dispensed an opioid at some point during pregnancy. There were 30,566 women (5.7%) dispensed an opioid during the first trimester, 30,434 women (5.7%) during the second trimester, and 34,906 women (6.5%) during the third trimester. Of these, 11,747 women (2.2%) were dispensed opioids three or more times during pregnancy. The most commonly dispensed opioids during pregnancy were hydrocodone (6.8%), codeine (6.1%), and oxycodone (2.0%). The prevalence of exposure at anytime during pregnancy decreased slightly during the study period from 14.9% for pregnancies that delivered in 2005 to 12.9% in 2011. The prevalence of exposure varied significantly by region and was lowest in the Northeast and highest in the South. CONCLUSIONS:This study demonstrates that opioids are very common exposures during pregnancy. Given the small and inconsistent body of literature on their safety in pregnancy, these findings suggest a need for research in this area.