Postpartum changes in methadone maintenance dose

The optimal approach to postpartum dosing among women treated with methadone maintenance is unclear. We examined doses among 101 methadone-maintained pregnant women 2, 6 and 12 weeks postpartum, and compared the incidence of having doses held for oversedation during pregnancy and postpartum. The average dose at delivery was 83.3mg, and the mean change from delivery to 12 weeks postpartum was -3.7 mg (95% CI -6.3, -1.1). The incidence of oversedation events per 10,000 days was 2.8 among pregnant women and 5.6 for postpartum women (incidence rate ratio [IRR] 2.04, 95% CI 0.66, 6.28). After adjusting for benzodiazepine prescriptions, the IRR of an oversedation event among postpartum women compared to pregnant women was 1.74 (95% CI 0.56, 5.30). In conclusion, postpartum dose changes were small in a methadone clinic using clinical assessments to determine dose. Although the incidence of oversedation events remained low postpartum, the clinically important but not statistically significant increase in events among postpartum women and those prescribed benzodiazepines requires further research. While there are not yet adequate data to support pre-specified postpartum dose reductions, the findings suggest that more frequent clinical assessments continuing as late as 12 weeks postpartum may be warranted.