Maternal educational inequalities in measured body mass index trajectories in three European countries

Background: Social inequalities in the prevalence of childhood overweight and obesity are well-established, but less is known about when the social gradient first emerges and how it evolves across childhood and adolescence. Objective: This study examines maternal education differentials in children's body mass trajectories in infancy, childhood and adolescence using data from four contemporary European child cohorts. Methods: Prospective data on children's body mass index (BMI) were obtained from four cohort studies—Generation XXI (G21—Portugal), Growing Up in Ireland (GUI) infant and child cohorts, and the Millennium Cohort Study (MCS—UK)—involving a total sample of 41,399 children and 120,140 observations. Children's BMI trajectories were modelled by maternal education level using mixed-effect models. Results: Maternal educational inequalities in children's BMI were evident as early as three years of age. Children from lower maternal educational backgrounds were characterised by accelerated BMI growth, and the extent of the disparity was such that boys from primary-educated backgrounds measured 0.42 kg/m² (95% CI 0.24, 0.60) heavier at 7 years of age in G21, 0.90 kg/m²(95% CI 0.60, 1.19) heavier at 13 years of age in GUI and 0.75 kg/m² (95% CI 0.52, 0.97) heavier in MCS at 14 years of age. The corresponding figures for girls were 0.71 kg/m² (95% CI 0.50, 0.91), 1.31 kg/m² (95% CI 1.00, 1.62) and 0.76 kg/m² (95% CI 0.53, 1.00) in G21, GUI and MCS, respectively. Conclusions: Maternal education is a strong predictor of BMI across European nations. Socio-economic differentials emerge early and widen across childhood, highlighting the need for early intervention.