Abstract
The first 1000 days have been recognized as a sensitive period that determines health in later stages of life. In high-income countries, lower socioeconomic status (SES) is associated with a higher risk of overweight/obesity (OW/OB) in childhood and adolescence. In low- and middle-income countries, this association is often reversed; however, longitudinal evidence remains scarce. We aimed to determine the risk of OW/OB up to age 15 years among adolescents according to SES at age 6–18 months in Peru, Vietnam, Ethiopia and India. Data from the younger cohort of the Young Lives study were analyzed. The incidence rate of OW/OB up to age 15 (measured at 5, 8, 12, and 15 years) was compared according to household wealth index at age 6–18 months. Crude and adjusted incidence rate ratios (IRRs) were estimated using generalized linear models of the Poisson family. The incidence rate of OW/OB per 100 person-years was 4.2, 1.4, 0.5 and 0.7 in Peru, Vietnam, Ethiopia and India, respectively. In all countries, and after adjusting for confounders, the risk of OW/OB was higher among participants from highest SES households (vs. their lowest SES counterparts), however these differences only held true at the population level in Peru [IRR: 1.9, 95% CI 1.4–2.5] and India [IRR: 3.3, 95% CI 1.7–6.7]. Sex-stratified analysis revealed that a higher SES was associated with higher risk of OW/OB in Peru, Vietnam and India among males, and in Peru, Ethiopia and India among females. Adolescents who lived in the highest SES households during the sensitive period of early childhood had a higher risk of OW/OB. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-025-33914-7.