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.