WEDNESDAY, Jan. 31, 2024 -- There's one treatment for pregnant women addicted to opioids that’s safer for their unborn child, a new study reports.

Buprenorphine is associated with a slightly lower risk of birth defects overall compared to methadone, according to findings published recently in the journal JAMA Internal Medicine.

However, the researchers stressed that expecting mothers with opioid use disorder (OUD) should use whichever treatment is available to them during both pregnancy and following delivery.

“I cannot emphasize enough that any opioid agonist therapy -- either buprenorphine or methadone -- is strongly recommended over untreated OUD during pregnancy,” said researcher Krista Huybrechts, an epidemiologist with Brigham and Women’s Hospital in Boston.

“The ultimate goal is to ensure continued access to effective treatment for a given patient during pregnancy as well as the postpartum period,” Huybrechts added in a hospital news release. “The small increase in the risk of malformations with methadone use compared to buprenorphine we observed likely does not exclude methadone as the best treatment choice for some pregnant individuals, particularly those on stable treatment prior to pregnancy or patients who do not respond well to buprenorphine.”

Between 2010 and 2017, the percentage of births affected by opioid addiction more than doubled, researchers said in background notes.

Opioid exposure in the womb has been linked to poor fetal growth, preterm birth, stillbirth and birth defects, they added.

Women are urged to get treatment for opioid addiction after they become pregnant, and the drugs buprenorphine and methadone are two common therapies.

Methadone is a synthetic medication that relieves drug cravings by acting directly on opioid receptors in the brain, but in a slower and more controlled way than illicit opioids like heroin, morphine or fentanyl, according to the National Institute on Drug Abuse (NIDA).

Buprenorphine works the same way, but activates opioid receptors even less strongly, NIDA says. Despite that, it’s been shown to be as effective as methadone if given in a sufficient dose.

In general, the choice of methadone or buprenorphine is influenced by factors like access to the drugs, patient preference and effectiveness, researchers said.

For this study, researchers decided to test another potential factor -- the comparative safety of buprenorphine versus methadone in pregnancy.

Researchers tracked more than 9,500 pregnancies covered by Medicaid where the woman used buprenorphine in the first trimester. These were compared to nearly 3,900 pregnancies where the woman used methadone.

The risk of birth defects was about 51 for every 1,000 pregnancies with buprenorphine, compared to nearly 61 per 1,000 for methadone.

Overall, buprenorphine carried an 18% lower risk during pregnancy then methadone, which translates to one less troubled pregnancy for every 100 patients treated with buprenorphine compared to methadone, results show.

“This should, however, not be taken to suggest that methadone should not be used in pregnancy,” Huybrechts said. “The comparative safety is one factor that should inform the treatment decision.”

More information

The National Institute on Drug Abuse has more about opioid addiction medications and opioid use in pregnancy.

SOURCE: Mass General Brigham, news release, Jan. 22, 2024