Trends of prenatal opioid utilization and neonatal abstinence syndrome in Manitoba, Canada: A 26-year population-based cohort study.

Background: Opioids are prescribed for pain and as opioid agonist therapy for opioid use disorder. This can lead to neonatal abstinence syndrome (NAS) in newborns when used in pregnancy. Few studies have described trends in prenatal opioid prescriptions and NAS by important determinants of health. Methods: To examine trends in prenatal opioid prescriptions and NAS diagnosis rates we conducted a population-based cohort study of live births in Manitoba, Canada, from January 1995 to March 2021. Live births were considered exposed to opioids prenatally if the pregnant person filled ≥1 opioid prescription during pregnancy. We described trends in NAS diagnosis rates by year, sex, urbanicity, and income quintile. Results: The cohort included 381,826 live births, of which 26,382 (6.7%) were exposed to prescription opioids prenatally. The proportion of live births exposed to opioid prescriptions during pregnancy increased from 3.7% in 1995 to 7.4% in 2017; however, there was a reduction in recent years. We identified a decrease in codeine prescriptions during pregnancy and an increased number of prescriptions for more potent opioids (oxycodone, hydromorphone, morphine, and opioid agonist therapy). During the study period, there were 1318 newborns diagnosed with NAS. The incidence of NAS in Manitoba more than tripled between 1995 and 2021 (2.0 to 7.6 per 1000 live births). Interpretation: The incidence of NAS increased over the study period, in line with other jurisdictions. Further research is needed to study the safety of different opioid agonist therapies and multidisciplinary support needed to support parents to care for newborns with NAS in the postpartum period and beyond.