Drug use in pregnancy in Ireland's capital city: A decade of trends and outcomes.

OBJECTIVE: The aim of this study was to present contemporary trends in opiate use disorder (OUD) and substance use in pregnancy in Ireland, with associated obstetric outcomes, over the last ten years. STUDY DESIGN: This retrospective observational cohort study was conducted at an Irish tertiary maternity unit. All women with OUD or substance use in pregnancy delivered under this service between 2010 and 2019 were included. Drug-exposure was self-reported. Data was collected by combining electronic and hand-held patient records. Trends and outcomes were analysed by year of delivery. Approval for the study was granted by the institution's clinical governance committee. RESULTS: Of the 82,669 women delivered, 525 had OUD or substance use in pregnancy (1 in every 160 women booking). 11.6% were homeless, 20.0% were in full-time employment and 91.0% smoked tobacco in pregnancy. 66.3% had a history of psychiatric disorders. Over the ten years, there was a significant reduction in women delivered with OUD or substance use in pregnancy (0.8 % to 0.4 %, RR 0.55, 95 % CI 0.36-0.85), significant reduction in the proportion of women on Opioid-Substitute-Treatment (OST, RR 0.66 95 % CI 0.51-0.87) and an increase in mean maternal age (30.7to32.0 years). Rates of cocaine and cannabis consumption increased (20.6 %, RR 3.8, 95 % CI 1.57-9.44: 24.0 %, RR 3.7, 95 % CI 1.58-8.86 respectively). The maternal mortality rate was 380.9:100,000 births. The perinatal mortality rate was 15.6:1000 births. The preterm birth rate was 17.9 %, with a mean birth weight of 2832 g. The rate of NICU admission was 52.0 % and the mean length of stay was 22.4 days. Amongst the smaller OUD population, the rate of NICU admission for Neonatal Abstinence Syndrome (NAS) and treatment for NAS increased over the study timeframe (36.0 %, RR 2.97, 95 % CI 1.86-4.75: 28.5 %, RR 2.92, 95 % CI 1.70-5.0 respectively). CONCLUSIONS: The obstetric population attending an Irish antenatal service with opiate use disorder or substance exposure is reducing in size with older patients, less opioid substitute therapy and increasing cocaine and cannabis use. These women have high rates of maternal and perinatal morbidity and mortality. Specialist antenatal addiction services, coordinated by the drug-liaison midwife, are critical in adapting care to respond to this dynamic and vulnerable patient cohort.