Atluru 2024: naltrexone vs buprenorphine or methadone in pregnancy

What they tested

The reviewers searched databases, conference proceedings and trial registries through May 2023 for studies comparing naltrexone (pills, implant or extended-release injection) with methadone or buprenorphine in pregnant people with opioid use disorder.

The main outcomes were gestational age at delivery, meaning how many weeks pregnant someone was at birth, and neonatal abstinence syndrome (NAS), withdrawal symptoms in the newborn. Substance use outcomes were also collected.

What they found

Five studies met the criteria: four looked back at records and one followed people forward. None was a randomized trial.

Four studies reported gestational age at delivery, and none found a difference between naltrexone and the other medicines (mean differences from -0.20 to 0.8 weeks).

All three studies that measured neonatal abstinence syndrome found a lower risk with naltrexone, with relative risks from 0.08 to 0.15. The confidence interval for the 0.08 figure ran from 0.01 to 1.16, so that result on its own was uncertain.

Four of the five studies had a moderate or high potential for selection bias, mainly because they were small and didn't control for confounders, other differences between the groups that could affect the results.

Limits

• There were only five studies, all observational, so the groups may have differed in ways that explain the results.
• Substance use outcomes couldn't be assessed well, and the authors call for more comparative studies.

What it means if you're considering naltrexone

For someone taking naltrexone who becomes pregnant, or weighing options in pregnancy, this review is cautiously reassuring. The authors call naltrexone a reasonable option for opioid use disorder in pregnancy with reassuring outcomes for parent and baby, while stressing that the evidence base is limited.