The biological and social determinants of childhood obesity: comparison of two cohorts 50 years apart.

Abstract Objective To determine whether the same relationships between early life risk factors and socioeconomic status with childhood BMI are observed in a modern cohort (2000) compared with an historic cohort (1947). Study design The relationships between early life factors and SES with childhood BMI were examined in two prospective birth cohorts from the same region, born 50 years apart: 711 children in the 1947 Newcastle Thousand Families Study (NTFS) and 475 from the 2000 Gateshead Millennium Study (GMS). The associations between birthweight, breastfeeding, rapid infancy growth (0-12 months), early life adversity (0-12 months) and parental SES (birth and childhood) with childhood BMI z-scores, and whether overweight/obese (BMI >91st centile using UK 1990) aged 9 were examined using linear regression, path analyses and logistic regression. Results In the NTFS, the most advantaged children were taller than the least (+0.91 height z-score, P = .001), whereas in GMS they had lower odds of overweight/obese than the least (0.35 (0.14, 0.86)). Rapid infancy growth was associated with increased BMIz in both cohorts, and with increased likelihood of overweight/obese in GMS. Conclusions This suggests that children exposed to socioeconomic disadvantage or who have rapid infancy growth in modern environments are now at lower risk of growth restriction, but greater risk of overweight.