Association Between Parental Social Position and Childhood Overweight: Mediation by Lifestyle and BMI Patterns During Pregnancy.

In high-income countries, children born to parents with low socio-economic position (SEP) or with non-Western ethnicity are disproportionally affected by obesity as early as preschool age. We assessed how much of these associations were mediated by parental lifestyle and BMI patterns during pregnancy. We characterised 5-6 years old children with or without overweight from the French Etude Longitudinale Française depuis l'Enfance (ELFE) (n = 8584) and the Dutch Generation R birth cohorts (n = 6511). We used counterfactual mediation analyses to assess the potential mediating effect of previously identified lifestyle patterns: "high parental smoking, poor-quality maternal diet and sedentary behaviour" and "high parental body mass index and low gestational weight gain". Both patterns jointly mediated 62.8% of the association between parents' education level and childhood overweight in ELFE and 23.2% in Generation R. In Generation R, they jointly mediated 8.9% of the association between parents' geographic origin and childhood overweight. In ELFE, parents with non-Western backgrounds were less likely to follow the first pattern, resulting in a negative indirect effect. Parental lifestyle and BMI patterns during pregnancy seem key contributors to the early development of socio-economic inequalities in childhood overweight, while other yet unidentified factors may contribute to inequalities related to geographic origin.