Weekly Buprenorphine Increased Opioid Abstinence in Pregnancy

Pregnant adults receiving extended-release buprenorphine in a recent clinical trial had higher rates of illicit opioid abstinence than those using daily sublingual buprenorphine.

The National Institute on Drug Abuse announced the findings on March 16, 2026, the same day the study was published in JAMA Internal Medicine.

The trial adds randomized evidence about a longer-acting form of an established medication for opioid use disorder. It also addresses maternal safety and neonatal opioid withdrawal syndrome, two concerns that require coordinated addiction and obstetric care during pregnancy.

How the Trial Compared Buprenorphine Formulations

Researchers randomized 140 pregnant adults at 13 outpatient peripartum opioid use disorder treatment sites. Sixty-nine participants received extended-release buprenorphine as a weekly injection under the skin, while 71 received sublingual buprenorphine, with or without naloxone. Postpartum participants who were not breastfeeding could receive a monthly extended-release formulation.

The open-label trial enrolled adults with moderate or severe opioid use disorder who had singleton pregnancies between six and 30 weeks of gestation. It ran from July 2020 through October 2024, with participants followed for up to 12 months postpartum. The National Institute on Drug Abuse supported the research through its Clinical Trials Network and the NIH HEAL Initiative.

Nearly all participants, 138 of 140, were already taking buprenorphine when randomized. The study therefore primarily compares formulations among people already receiving medication, rather than evaluating how to begin buprenorphine during medical detox.

Extended-Release Buprenorphine Results During Pregnancy

During pregnancy, 82.5% of urine samples in the extended-release group were negative for illicit opioids, compared with 72.6% in the sublingual group. The mean difference was 9.84 percentage points. Researchers first established noninferiority, then found that the extended-release formulation was statistically superior for this primary outcome.

Medication adherence during pregnancy was similar, at 84.4% of days in the extended-release group and 84.9% in the sublingual group. Craving and withdrawal scores were low in both groups, and the pregnancy-phase differences in those measures were not statistically significant.

Postpartum, Safety, and Newborn Outcomes

The pregnancy advantage did not continue as a statistically significant difference after delivery. Postpartum illicit opioid abstinence rates were 60.2% with extended-release treatment and 59.5% with sublingual treatment. Adherence and broader drug and alcohol abstinence also did not differ significantly between groups postpartum.

Serious maternal adverse events were less common in the extended-release group during pregnancy, at 8.7% versus 26.8%, and postpartum, at 6.0% versus 18.6%. Overall rates of nonserious maternal adverse events did not differ.

However, more nonserious events during pregnancy were classified as medication-related in the extended-release group, 26.1% compared with 7.0%. The researchers noted that judging whether an event is medication-related can be unreliable, particularly in an open-label trial.

Neonatal opioid withdrawal outcomes did not significantly differ. Opioid treatment for neonatal withdrawal was used for 30.2% of infants in the extended-release group and 26.5% in the sublingual group. Average treatment durations of 10.9 and 14.8 days, respectively, were also not significantly different.

What the Findings Do Not Establish

The authors cautioned that some secondary outcomes may have been underpowered. Medical-record outcomes had more missing data and potential quality issues, including variation in neonatal withdrawal scoring among hospitals.

Most participants were clinically stable and already receiving buprenorphine, so it is unclear whether the findings apply to people with less stable opioid use disorder or those starting the medication. The largely White, non-Hispanic sample also limits the generalizability of the findings to more racially and ethnically diverse populations.

Medical Supervision and Continuing Care

Pregnant people considering a change in buprenorphine formulation should make that decision with clinicians who understand both opioid use disorder and pregnancy.

No one should stop or switch prescribed medication without medical guidance. Untreated opioid use disorder can carry serious risks, while neonatal opioid withdrawal requires informed planning and appropriate newborn care.

Medical detox alone is not a complete treatment plan. Ongoing medication, prenatal care, postpartum follow-up, and behavioral health support can be coordinated around individual needs. Call 800-996-6135Sponsored to discuss medically supervised withdrawal and continuing treatment options, or contact SAMHSA’s National Helpline at 1-800-662-4357 for free, confidential referrals.