New Study Found No Adverse Outcomes in Infants of Mothers Prescribed Opioids Postpartum, Including Death

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A new study found no association between maternal opioid prescription after delivery and several adverse infant outcomes, including rehospitalization, emergency department visits, and death.

“Most mothers in North America initiate breastfeeding in the immediate postpartum period,” wrote authors in The BMJ. “All opioids pass into breast milk in small amounts, although not in quantities expected to cause respiratory or central nervous system depression in nursing infants. Isolated reports describe opioid toxicity in breastfed infants, which some authors have hypothesized reflects the ingestion of large quantities of opioids in breast milk.”

While the plausibility of those isolated reports has been repeatedly questioned, there are still concerns about the possibility of breastfeeding-related opioid toxicity in infants. “This uncertainty might undermine postpartum analgesia and generate unnecessary anxiety for parents. Whether maternal opioid use while breastfeeding truly presents a risk to newborn infants remains the subject of debate,” wrote researchers who were led by Jonathan S. Zipursky, MD, PhD, assistant professor at Sunnybrook Health Sciences Centre in Toronto.

Zipursky and colleagues conducted a retrospective cohort study to investigate whether postpartum maternal opioid treatment is associated with short-term increased risk of adverse outcomes in infants. The research team analyzed 8 years of health care data obtained from the ICES MOMBABY database, which links children born in Ontario hospitals to their mothers. They also used the Narcotics Monitoring System and the National Ambulatory Care Reporting System databases to identify prescriptions for postpartum opioids.

Participants included 865 691 mother-infant pairs discharged from the hospital within 7 days of delivery between September 1, 2012, and March 31, 2020. Researchers identified 85 852 mothers who had filled an opioid prescription between delivery and up to 7 days after being discharged from the hospital. Each mother who filled an opioid prescription was propensity score matched to one who did not fill an opioid prescription. Opioids prescribed included oxycodone, codeine, morphine, and hydromorphone, with an average supply of 3 days.

The primary outcome was hospital readmission of infants for any reason within 30 days of their mother filling an opioid prescription. Secondary outcomes included any emergency department visit, hospital admission for any injury, admission to the neonatal intensive care unit, hospital admission with resuscitation or assisted ventilation, and all-cause death.

Findings

Of the infants admitted to the hospital within 30 days of birth, 2962 (3.5%) were born to mothers who filled an opioid prescription and 3038 (3.5%) were born to mothers who did not fill an opioid prescription.

Infants of mothers who were prescribed an opioid were more likely to be admitted to the hospital for any reason than infants of mothers who were not prescribed an opioid (hazard ratio [HR] 0.98, 95% CI 0.93-1.03) and slightly more likely to be taken to an emergency department in the subsequent 30 days (HR 1.04, 95% CI 1.01-1.08). There were no differences between the 2 groups in all other secondary outcomes, and no deaths occurred in either group.

“Our findings indicate that readmission of infants to hospital is no more likely among those born to mothers prescribed opioids after delivery than among those born to mothers not prescribed opioids after delivery,” wrote Zipursky and colleagues.

Investigators noted several limitations of the study, including the fact that they had no information regarding how much of the opioids the mothers took after filling the prescriptions and the cohort is likely to include mothers who were and were not breastfeeding. “We acknowledge that avoidance or minimization of breastfeeding in mothers using opioids after delivery would limit our ability to detect any true association between maternal postpartum opioid use and opioid toxicity in infants,” wrote researchers.

Although the research team found no increased risk of harm in infants born to mothers prescribed opioids postpartum, they noted that their findings “should not be construed as an endorsement of liberal postpartum opioid use.”

Reference: Zipursky JS, Gomes T, Everett K, et al. Maternal opioid treatment after delivery and risk of adverse infant outcomes: Population based cohort study. BMJ. 2023;380:e074005.