1. No association was found between maternal opioid treatment in the immediate postpartum period and adverse outcomes in infants after 30 days.
Evidence Rating Level: 2 (Good)
Study Rundown: Opioid toxicity is not currently thought to be an adverse effect in infants breastfed from mothers requiring opioids for immediate postpartum analgesia, due to the low levels of opioids diffusing into breast milk. However, there is ongoing concern and uncertainty, as seen in health regulatory bodies that recommend caution when using opioids when breastfeeding in the postpartum period. Therefore, this propensity-matched cohort study based in Ontario, Canada aimed to elucidate the association between prescribed maternal opioid use after delivery and adverse outcomes in infants. Study participants included maternal-infant pairs over an 8-year period, divided into two cohorts, depending on whether they filled an opioid prescription within 7 days of delivery. There were 85,675 participants in each cohort, and the primary outcome was readmission of the infant to hospital for any reason after 30 days. No data on breastfeeding status was available in this study. Overall, the study found no difference in readmission rates between the cohort that filled an opioid prescription and the cohort that did not, as well as no differences in adverse infant events or infant death.
Relevant Reading: Opioids in Breast Milk: Pharmacokinetic Principles and Clinical Implications
In-Depth [retrospective cohort]: This study included mothers with singleton liveborn deliveries at an Ontario hospital between 2012 and 2020, with mother and infant discharged on the same day, and within 7 days of delivery. Only a mother’s first delivery within the study period was included. Participants in each cohort were propensity-matched based on age, year of delivery, and method of delivery. Outcomes assessed for infants included readmission for any reason, visits to the emergency room, admission for injury, admission to the NICU, admission with resuscitation or ventilation required, and death. These outcomes were assessed at 30 days after the index date, which was the date of prescription fill for the opioid prescription cohort, or a simulated date also within 7 days of delivery for those in the cohort without an opioid prescription. In total, there were 85,675 mothers in each cohort. The study found a rate of 3.5% for infants readmitted to hospital, the same rate in both cohorts (hazard ratio 0.98, 95% CI 0.93-1.03). The reasons for readmission also did not differ between cohorts. In terms of secondary outcomes, there was a marginally increased likelihood of infant emergency visits in the opioid prescription cohort (HR 1.04, 95% CI 1.01-1.08), but no difference in other outcomes, including admission for injury (HR 1.24, 95% CI 0.92-1.67), admission to NICU (HR 1.12, 95% CI 0.94-1.23), admission with resuscitation or ventilation required (HR 0.87, 95% CI 0.60-1.26), and death (no events in either cohort). Overall, this study found no association with maternal opioid prescription and adverse outcomes for infants in the immediate postpartum period.
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