Abstract

Context—The association between low socioeconomic status (SES) and childhood obesity foreshadows life-long inequalities in health. Insight into the causal mechanisms linking childhood adversity to long-term health could be provided by discovering when the negative SES gradient in weight emerges, and what early life experiences are associated with it. Objective—To examine SES differences in infant weight gain in the first three months of life, and assess contributions of parental BMI, maternal smoking, and feeding method to this association. Design—Observational study using longitudinal weight data from 2402 families taking part in the Gemini study; a twin birth cohort recruited from all twin births between March and December 2007 in England and Wales. Outcome Measures—Infant weights at birth and three months converted to standard deviation scores (SDS), change in weight SDS, and rapid growth. SES was indexed by occupation and maternal education. Results—There were no SES differences in birth weight, but lower SES was associated with