ABSTRACT
Background: There is minimal information about the association of head growth at different stages of childhood with cognitive ability. Objective: To determine the relationship of newborn head size and head growth during infancy, childhood and adolescence with attained education, a proxy for cognitive ability. Study design: Prospective birth cohort study. Setting: Married women living in South Delhi between 1969 and 1973. Participants: The New Delhi Birth Cohort study followed up 8030 newborns born in 1969-1973 with head circumference, weight and height measurements at birth and 6-12 monthly until adulthood. Of these, 1526 men and women were followed up at the age of 26-32 years. Outcomes: Association between years of schooling, as an indicator of cognitive ability, and newborn head circumference and conditional measures of head growth during infancy, childhood and adolescence. Results: In unadjusted analyses, newborn head size was positively associated with years of education [(? (95% CI)=0.30 (0.14 to 0.47) years per SD head circumference], as was head growth from birth to 6 months [? (95% CI)=0.44 (0.28 to 0.60) years per SD conditional head growth], 6 months to 2 years [? (95% CI)=0.31 (0.15 to 0.47) years per SD conditional head growth] and 2 to 11 years [? (95% CI)=0.20 (0.03 to 0.36) years per SD conditional head growth]. There were similar findings for height and body mass index (BMI). In the adjusted model containing all growth measures, gestational age, and socioeconomic status (SES) at birth as predictors, only SES was positively associated with educational attainment. Conclusion: Educational attainment in this population is positively associated with socioeconomic status and its influence on inter-related early life (fetal, infant and childhood) factors like nutritional status and brain growth.