Growth during the first year of life following prenatal opioid exposure: A retrospective cohort study

Objectives: Opioid use during pregnancy is common and has been shown to affect fetal growth, increasing from 6.5 to 23 per 1,000 live births over the past decade. Prenatal exposure to opioids can result in neonatal opioid withdrawal syndrome (NOWS) and is associated with a higher incidence of fetal growth restriction, including lower weight, shorter length, and smaller head circumference at delivery. The goal of the current study was to determine whether growth deficits observed at birth in opioid-exposed infants persisted over the first year of life. Methods: This study retrospectively reviewed charts from two university-affiliated pediatric practices in the Midwestern United States. Data were drawn from a larger study that screened medical records of pediatric patients born after July 2016. The study included infants whose mothers used opioids during pregnancy and unexposed controls. Results: A total of 242 participants were included: 53 opioid-exposed infants (2 of whom developed NOWS) and 189 controls. Compared with controls, exposed infants were 4 times as likely to be diagnosed with intrauterine growth restriction (18.9% vs 5.3%; adjusted OR = 4.07; 95% CI, 1.59–10.40). The lower length percentile observed at birth remained significant through 1 year of age ( P < 0.01), even after adjustment for confounders. Differences in weight and head circumference were smaller and not statistically significant. Conclusions: Lower length percentiles in opioid-exposed children persisted beyond the neonatal period, whereas some catch-up in weight was observed during the first year of life and the difference in head circumference did not persist. These findings emphasize the importance of continued monitoring and early interventions in opioid-exposed infants, especially to address persistent linear growth restriction beyond the neonatal period, even in the absence of NOWS.