Methadone to manage pain in pregnancy at Te Toka Tumai Auckland City Hospital: A retrospective observational analysis

Pain during pregnancy is common, yet evidence-based management remains limited. While non-pharmacological treatments are first-line, severe pain may necessitate pharmacological intervention. Methadone is well studied for opioid use disorder, but its role in acute pain management during pregnancy is less defined. This retrospective observational study examined pregnant patients prescribed low-dose methadone for pain management between January 2022 and December 2023 at a tertiary multidisciplinary pain service. Patients receiving opioid substitution therapy were excluded. Data on methadone dosing, pain scores, maternal side effects, and neonatal outcomes were analysed. Twenty-three patients were identified, with 22 included in the analysis. The mean gestation at methadone initiation was 29.7 weeks (standard deviation 5.1), and the median starting dose was 5 mg per day (interquartile range 2.5 to 5). Pain severity decreased significantly: the proportion reporting severe pain at rest fell from 82% to 14% at 48 hours (absolute risk reduction (ARR) 68%, number needed to treat (NNT) 2), and the proportion reporting severe pain with movement fell from 95% to 32% (ARR 64%, NNT 2), with sustained improvement at 4 weeks. Side-effects included sedation (14%) and nausea (23%) and were generally well tolerated. Among 19 neonates, no cases of neonatal abstinence syndrome were observed. Six required neonatal intensive care unit admission, but none for opioid withdrawal. These findings suggest that low-dose methadone, when used within a closely monitored multidisciplinary setting, may provide effective pain relief in the pregnant patient without significant neonatal harm. However, this high level of oversight may limit generalisability to other care settings. Further research is warranted to guide safe implementation and optimise dosing.