NICU-Based Stress Response and Preterm Infant Neurobehavior - Exploring the Critical Windows for Exposure

BACKGROUND: Exposure to maternal stress in utero negatively impacts cognitive and behavioral outcomes of children born at term. The neonatal intensive care unit (NICU) can be stressful for preterm infants during a developmental period corresponding to the third trimester of gestation. It is unknown whether stress in the NICU contributes to adverse neurodevelopment among NICU graduates. OBJECTIVE: To examine the association between salivary cortisol and early neurodevelopment in preterm infants. DESIGN/METHODS: We examined the association between cortisol levels during the NICU hospitalization and subsequent performance on the NICU Network Neurobehavioral Scales (NNNS), estimating time-specific associations and considering sex differences. RESULTS: 840 salivary cortisol levels were measured from 139 infants. Average cortisol levels were inversely associated with NNNS Regulation scores for both male and female infants (β=−0.19; 95% CI: −0.44, −0.02). Critical developmental windows based on postmenstrual age were identified, with cortisol measured < 30 weeks PMA positively associated with Habituation and Lethargy scores (β=0.63–1.04). Critical developmental windows based on chronological age were identified, with cortisol measured in the first week of life inversely associated with Attention score (β=−1.01 for females; −0.93 for males). CONCLUSION(S): Stress in the NICU at specific developmental time points may impact early preterm infant neurodevelopment.