Prescription drug use among pregnant women in opioid Maintenance Treatment.

AIMS This study describes the use of prescribed drugs among women in opioid maintenance treatment (OMT) prior to, and during, pregnancy. DESIGN This cohort study was based on data from two nationwide databases: the Medical Birth Registry of Norway and the Norwegian Prescription Database. SETTING Norway, 2004-2010. PARTICIPANTS OMT drugs were dispensed to 138 women with 159 pregnancies. MEASUREMENTS All prescription drugs dispensed to women in OMT three months prior to, and during, pregnancy were studied. Amounts of benzodiazepines, z-hypnotics and opioid analgesics dispensed during pregnancy were studied and bivariate analysis was used to study neonatal outcomes of OMT pregnancies with and without such co-medication. FINDINGS The prevalence of prescription drug use by pregnant OMT women was high both during the three-month period prior to (69%), and during (81%), pregnancy. The proportion of pregnant women that was dispensed anti-infectives (48%) and/or drugs acting on the nervous system (45%) during any time in pregnancy was especially high. In 21%, 15% and 13% of the pregnancies the women were dispensed benzodiazepine anxiolytics, opioid analgesics or benzodiazepine hypnotics respectively. Only 5% of the OMT women were dispensed antidepressants. Malformations were significantly more common among children born to mothers in OMT that received co-medication with opioids, benzodiazepines or z-hypnotics. CONCLUSIONS A higher proportion of women in opioid maintenance treatment in Norway use prescription drugs prior to, and during, pregnancy than pregnant women in the general population. Co-medication with drugs with abuse potential may increase the risk of adverse pregnancy outcomes and this need to be further addressed.