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 [(b (95% CI)=0.30 (0.14 to 0.47) years per SD head circumference], as was head growth from birth to 6 months [b (95% CI)=0.44 (0.28 to 0.60) years per SD conditional head growth], 6 months to 2 years [b (95% CI)=0.31 (0.15 to 0.47) years per SD conditional head growth] and 2 to 11 years [b (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 socio-economic 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.