Background: In total, 3.1 million young children die every year from under-nutrition. Greater understanding of associations between socio-economic status (SES) and the biological factors that shape under-nutrition are required to target interventions.
Aim: To establish whether SES inequalities in under-nutrition, proxied by infant size at 12 months, operate through maternal and early infant size measures.
Subjects and methods: The sample comprised 347 Indian infants born in 60 villages in rural Andhra Pradesh 2005-2007. Structural equation path models were applied to decompose the total relationship between SES (standard of living index) and length and weight for age Z-scores (LAZ/WAZ) at 12 months into direct and indirect (operating through maternal BMI and height, birthweight Z-score and LAZ/WAZ at 6 months) paths.
Results: SES had a direct positive association with LAZ (Standardised coefficient = 0.08, 95% CI = 0.02-0.13) and WAZ at age 12 months (Standardised coefficient = 0.08, 95% CI = 0.02-0.15). It also had additional indirect positive associations through increased maternal height and subsequently increased birthweight and WAZ/LAZ at 6 months, accounting for 35% and 53% of the total effect for WAZ and LAZ, respectively.
Conclusion: Findings support targeting evidence based growth interventions towards infants from the poorest families with the shortest mothers. Increasing SES can improve growth for two generations.
Keywords: Birthweight; infant growth; maternal BMI; maternal height; socio-economic status; structural equation modeling.