Maternal and neonatal outcomes following methadone substitution during pregnancy

Purpose To assess the maternal and neonatal outcomes of pregnant women enrolled on a Methadone Substitution Programme (MSP). Design Retrospective cohort study. Setting Maternity unit of a London teaching hospital and tertiary referral centre. Subjects Pregnant women on a MSP whose antenatal care and delivery was at St Thomas' Hospital (STH) between January 2005 and March 2008. Controls were non-MSP mothers closely matched for age, parity and delivery date during the same period. Methods Maternal data was collected from the Liaison Antenatal Drugs and Alcohol Service clinic records and the STH Maternity Unit's computerised database. Neonatal data was extracted from the STH Neonatal database (part of the UK National Neonatal database). Outcome Measures Maternal profiles (age, gravidity, parity, ethnicity, BMI, smoking and alcohol history, relationship and employment history), pregnancy details and mode of delivery. Neonatal outcome measures to include gestation age at delivery, birth weight, head circumference, admission rates and length of stay on Special Care Baby Unit plus Neonatal Abstinence Syndrome (NAS) rates, scoring and treatment. Results Compared to the non-MSP mothers (n = 88) the MSP group (n = 44) booked later and had a higher incidence of smoking (6.8 vs. 84.1 %), alcohol consumption (10.2 vs. 34.1 %). As a group, they had adverse social background. The MSP group had a higher relative risk (RR) of premature delivery [RR = 2.5, 95% confidence interval (CI) 1.66-3.88] and had lower birth weight babies (adjusted RR = 2.2; 95% CI 1.31-3.71) with smaller head circumferences (adjusted RR 1.9; 95% CI 1.06-3.38). NAS occurred in 27 % (95% CI 15.0-42.8) of the MSP group. There was no difference in congenital abnormality between the two groups, but caesarean section rate was higher in the control group. Conclusion Opiate-addicted mothers have adverse perinatal outcomes even on MSPs. In addition to the drug effect associated social, relationship and accommodation problems should also be addressed as they may affect the outcome. Pregnancy care for these women needs to continue to develop to improve overall outcomes.