Objective To determine the extent that social variables influence cognitive development of very low birth weight (VLBW) infants across the preschool years. Study design Participants were VLBW (500-1250 g) children enrolled in the Caffeine for Apnea of Prematurity randomized trial between 1999 and 2004. We investigated the relationships between 4 potential social advantages: higher maternal education, higher paternal education, caregiver employment, and 2 biologic parents in the same home'and gain in cognitive scores. Cognitive assessments were performed at the corrected ages of 18 months (Mental Development Index score on the Bayley Scales of Infant Development II) and 5 years (Full Scale IQ on the Wechsler Preschool and Primary Scale of Intelligence III). Cognitive gain was computed by subtracting each individual 18-month Mental Development Index score from the corresponding Full Scale IQ at 5 years. Results Data were available for 1347 children. Mean (SD) cognitive scores were 90.8 (15.7) at 18 months and 98.9 (14.5) at 5 years. Multivariable regression showed that higher maternal education, higher paternal education, and caregiver employment had independent and additive effects of similar size on cognitive gain (P < .001); the mean cognitive gain between 18 months and 5 years increased by 3.6 points in the presence of each of these advantages. When all 3 were present, cognitive scores improved on average by 10.9 points compared with children without any of these advantages. Conclusion In VLBW children, a count of 3 social advantages strongly predicts gains in cognitive scores across the preschool years.
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