When treating opioid use disorder (OUD) during pregnancy, the risk for major congenital malformations is lower with buprenorphine than methadone. These study results, published in JAMA Internal Medicine, may help inform prescribing decisions for physicians treating pregnant individuals with OUD.
Given the escalating prevalence of opioid misuse and long-term opioid use among pregnant patients in the United States, there is a critical need to optimize treatment for OUD during pregnancy to mitigate risks like overdose, opioid exposure, and withdrawal symptoms. Despite clinical evidence favoring buprenorphine over methadone for reducing the risk for neonatal abstinence syndrome, preterm birth, and low birth weight, data regarding the risk for congenital malformations associated with these treatments during pregnancy are limited. The current study sought to assess the comparative risk for congenital malformations among infants exposed to buprenorphine vs methadone during the first trimester.
Researchers used data from a nationwide cohort of Medicaid-insured pregnancies and linked infant records between 2000 and 2018. The researchers used dispensing records in the first trimester to identify buprenorphine-exposed pregnancies and administration codes in the first trimester to identify pregnancies exposed to methadone. The primary outcome of interest was the composite outcome of all major congenital malformations. The researchers also evaluated specific malformations previously associated with opioid use and potential confounders, including OUD history, OUD severity, nonopioid dependence, demographics, and comorbid conditions.
It should be highlighted that any opioid agonist therapy — either buprenorphine or methadone — is strongly recommended over untreated OUD during pregnancy.
Overall, 9514 pregnancies were exposed to buprenorphine in the first trimester and 3846 were exposed to methadone. The researchers observed that the risk for any major congenital malformation was 50.9 (95% CI, 46.5-55.3) per 1000 pregnancies in the buprenorphine group and 60.6 (95% CI, 53.0-68.1) per 1000 pregnancies in the methadone group. After adjusting for confounders, buprenorphine was associated with a lower relative risk (RR) for malformations compared with methadone (RR, 0.82; 95% CI, 0.69-0.97).
For specific malformations associated with opioid exposure, those exposed to buprenorphine had a decreased risk for central nervous system (RR, 0.51; 95% CI, 0.30-0.89), urinary (RR, 0.62; 95% CI, 0.37-1.04), and limb (RR, 0.53; 95% CI, 0.34-0.83) malformations, relative to methadone-exposed infants. However, buprenorphine was associated with a higher risk for gastrointestinal malformation (RR, 1.98; 95% CI, 1.15-3.39).
Data from this large cohort of Medicaid beneficiaries indicates that buprenorphine use for the treatment of OUD in the first trimester of pregnancy is associated with a decreased risk for major congenital malformations relative to methadone. Study authors concluded, “It should be highlighted that any opioid agonist therapy — either buprenorphine or methadone — is strongly recommended over untreated OUD during pregnancy.”
Study limitations include the potential underreporting of medications for opioid use disorder not covered by Medicaid, a lack of methadone dose data, and small event counts for certain malformations.
Note: This article originally appeared on Psychiatry Advisor
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