Buprenorphine use during pregnancy linked to better neonatal outcomes

The use of buprenorphine during pregnancy appears to be associated with a lower risk of adverse neonatal outcomes compared with methadone use. However, adverse maternal outcomes are similar for both therapies, according to a recent study.

“We observed strong inverse associations between buprenorphine use in pregnancy and neonatal outcomes, such as neonatal abstinence syndrome, preterm birth, small size for gestational age, and low birth weight, as compared with methadone use,” said the researchers.

It is well known that either buprenorphine or methadone, an opioid agonist therapy, is the standard of care for treating pregnant persons with opioid use disorder (OUD). In particular, it has been shown that buprenorphine may be associated with more favourable neonatal outcomes than methadone, but existing data are limited, the researchers noted.

Using data from the large, nationwide Medicaid database between 2000 and 2018 in the US, the researchers identified 10,704 and 4,387 pregnant women with OUD who were exposed to buprenorphine or methadone, respectively. Exposure to therapy was assessed during early pregnancy (through gestational week 19), late pregnancy (gestational week 20 through the day before delivery), and the 30 days before delivery. [N Engl J Med 2022;387:2033-2044]

Neonatal outcomes

Infants who were born to mothers exposed to buprenorphine within 30 days before delivery had a lower risk of neonatal abstinence syndrome than those born to mothers who were exposed to methadone (52.0 percent vs 69.2 percent; adjusted relative risk [adjRR], 0.73).

A lower risk of preterm birth (14.4 percent vs 24.9 percent; adjRR, 0.58), small size for gestational age (12.1 percent vs 15.3 percent; adjRR, 0.72), and low birth weight (8.3 percent vs 14.9 percent; adjRR, 0.56) was also observed among infants born to mothers who received buprenorphine compared to those who received methadone during early pregnancy.

Maternal outcomes

There was no difference in the risk of Caesarean delivery (33.6 percent vs 33.1; adjRR, 1.02) and severe maternal complications (3.3 percent vs 3.5 percent; adjRR, 0.91) among those who were exposed to buprenorphine or methadone during early pregnancy.

The results of exposure in late pregnancy were consistent with that observed during early pregnancy, noted the researchers.

“Overall, our results support the findings of the MOTHER* trial that buprenorphine exposure in utero results in more favourable outcomes for neonates than methadone exposure,” said the researchers.

“Opioid agonist therapy is strongly recommended for pregnant persons with OUD, and any opioid agonist therapy is recommended over untreated OUD during pregnancy, because untreated persons have greater incidence of adverse outcomes owing to withdrawal, return to opioid use, overdose, intravenous drug use, and inadequacy of prenatal care,” they noted.

*MOTHER: Maternal Opioid Treatment: Human Experimental Researcher