Growth in the neonatal intensive care unit influences neurodevelopmental and growth outcomes of extremely low birth weight infants

Abstract

Objectives: The objectives of this study were to assess whether (1) in-hospital growth velocity is predictive of neurodevelopmental and growth outcomes at 18 to 22 months' corrected age among extremely low birth weight (ELBW) infants and (2) in-hospital growth velocity contributes to these outcomes after controlling for confounding demographic and clinical variables.

Methods: Infants 501 to 1000 g birth weight from a multicenter cohort study were divided into quartiles of in-hospital growth velocity rates. Variables considered for the logistic-regression models included gender, race, gestational age, small for gestational age, mother's education, severe intraventricular hemorrhage, periventricular leukomalacia, age at regaining birth weight, necrotizing enterocolitis, late-onset infection, bronchopulmonary dysplasia, postnatal steroid therapy for pulmonary disease, and center.

Results: Of the 600 discharged infants, 495 (83%) were evaluated at 18 to 22 months' corrected age. As the rate of weight gain increased between quartile 1 and quartile 4, from 12.0 to 21.2 g/kg per day, the incidence of cerebral palsy, Bayley II Mental Developmental Index (MDI) <70 and Psychomotor Developmental Index (PDI) <70, abnormal neurologic examination, neurodevelopmental impairment, and need for rehospitalization fell significantly. Similar findings were observed as the rate of head circumference growth increased. The in-hospital rate of growth was associated with the likelihood of anthropometric measurements at 18 months' corrected age below the 10th percentile values of the Centers for Disease Control and Prevention 2000 growth curve. Logistic-regression analyses, controlling for potential demographic or clinical cofounders, and adjusted for center, identified a significant relationship between growth velocity and the likelihood of cerebral palsy, MDI and PDI scores of <70, and neurodevelopmental impairment.

Conclusions: These analyses suggest that growth velocity during an ELBW infant's NICU hospitalization exerts a significant, and possibly independent, effect on neurodevelopmental and growth outcomes at 18 to 22 months' corrected age.