Early Life Factors Associated with Neurobehavioral Outcomes in Preterm Infants during NICU Hospitalization

BACKGROUND. To investigate the influence of early life pain/stress and medical characteristics on neurobehavioral outcomes in preterm infants. METHODS. A prospective cohort study was conducted with 92 preterm infants (28–32 weeks gestational age [GA]). Early life pain/stress was measured via the Neonatal Infant Stressor Scale (NISS) during the first 28 days of NICU hospitalization. Neurobehavioral outcomes were evaluated using the NICU Network Neurobehavioral Scale at 36–38 weeks post-menstrual age. Functional regression and machine learning models were performed to investigate the predictors of neurobehavioral outcomes. RESULTS. Infants experienced daily acute pain/stress (24.99±7.13 frequencies) and chronic events (41.13±17.81 hours). Up to 12 days after birth, both higher acute and chronic NISS scores were associated with higher stress scores; and higher chronic NISS scores were also related to lower self-regulation and quality of movement. Younger GA predicted worse neurobehavioral outcomes, GA < 31.57 weeks predicting worse stress/abstinence, self-regulation, and excitability; GA < 30.57 weeks predicting poor quality of movement. A higher proportion of maternal breastmilk intake predicted better self-regulation, excitability, and quality of movement in older GA infants. CONCLUSION. Preterm infants are vulnerable to the impact of early life pain/stress. Neurobehavioral outcomes are positively associated with increased GA and higher maternal breastmilk intake.