(278) Maternal opioid use during breastfeeding and the risk of adverse infant outcomes: A nationwide cohort study among 4 million mother-child dyads

Background: Opioids are prescribed for pain management after childbirth, yet the impact of maternal opioid use during breastfeeding on newborns remains a subject of ongoing debate, mainly complicated with publicized case report. This uncertainty could potentially undermine the effectiveness of postpartum analgesia, thus, necessitates clarification.

Objectives: To investigate whether maternal opioid exposure during lactation is associated with an increased risk of adverse infant outcomes

Methods: We conducted a nationwide cohort study using Korea’s National Health Insurance Service (NHIS) claims database between 2009-2021. We included all women who fully or partially breastfed their infants, identified in the National Health Screening Program, after giving live birth. We defined exposure as opioid or comparator drugs (non-opioid; acetaminophen or NSAIDs), with infants followed from the date of the mother's first prescription of either drugs within four months postpartum until the earliest day of outcome occurrence, death, or end of 3 months. The outcome was composite of any emergency department or hospital visit for apnea or respiratory depression of newborn. Hazard ratios (HRs) with a 95% confidence interval (CI) were estimated using Cox proportional hazards regression with propensity score fine stratification to adjust for potential confounders. Subgroup analyses were conducted according to each specific opioid and history of opioid prescription during pregnancy. Further, additional analyses were performed; 1) restriction to women who have exclusive breastfeeding, 2) same analysis with imputed data to address missing data on breastfeeding status.

Results: Among 55,143 (mean [SD] age, 31.6 [4.1] years) opioid-prescribed mothers and 355,960 (31.8 [4.0] years) non-opioid prescribed mothers who breastfed their children, 311 (0.56%) children born to the opioid group experienced the outcome in the subsequent 3 months, compared with 1,967 (0.55%) in the non-opioid group. No significant increase of risk in infants of opioid-prescribed mothers versus those prescribed non-opioids was observed (weighted HR, 1.03; 95% CI, 0.91-1.16). For the subgroup analyses, there was no association according to individual opioid, but marginally elevated risks were shown for fentanyl and morphine. The result was similar with opioid-naïve women during pregnancy (0.94, 0.80-1.10), and remained consistent across a broad range of additional analyses.

Conclusions: Findings from this study suggest no association between maternal opioid prescription during breastfeeding and opioid-induced adverse outcomes among their infants. This real-world evidence helps inform patients and practitioners regarding the management of postpartum pain in routine clinical practice.