Full title: prevalence and risk factors of overweight in Beijing infants basing generalized estimating equation: a longitudinal study.

Background: The prevalence of childhood overweight and obesity in China has been rapidly increasing in recent years. The purposes of this study were to investigate the prevalence of infant overweight in Beijing and to explore the influencing factors using a generalized estimating equation (GEE) model.

Methods: This is a birth cohort study from January 2022 to December 2022 in Beijing, involving 2,008 newborns from local residents. Four times of follow-up visits were conducted at 2, 5, 8, and 12 months of age for physical measurements and health information collection. Multiple exposures were considered, including demographic characteristics of infants, maternal pregnancy information, feeding pattern and outdoor activities of infants. The GEE model was utilized to identify influencing factors for infant overweight while adjusting for potential confounders.

Results: The prevalence of overweight for 2-, 5-, 8-, and 12-month-old infants were 14.4%, 21.6%, 24.4%, and 24.2%, respectively. Among the influencing factors, irregular exercise during pregnancy (OR = 1.190, P = 0.045), mixed feeding or artificial feeding (non-exclusive breastfeeding) (OR = 1.233, P = 0.025), high birth weight (OR = 1.468, P < 0.001), and high pre-pregnancy body mass index (BMI) (OR = 2.113, P = 0.005) were positively correlated with infant overweight. Conversely, weight gain ≤ 15.0 kg during pregnancy (OR = 0.778, P = 0.016), high birth length (OR = 0.990, P = 0.003), and longer duration of outdoor activity for infants (OR = 0.764, P < 0.001) were negatively correlated with infant overweight.

Conclusions: Our findings suggest certain factors are associated with infant overweight risk. Further research is required before making causal inferences and formulating preventive strategies for infant overweight.