Supplementary Material for: Causal associations of gestational and perinatal factors with the risk of childhood obesity: A Mendelian Randomization study

Introduction: This study was to explore the causal association between gestational and perinatal factors and the risk of childhood obesity based on two-sample Mendelian Randomization (MR).
Methods: The single-nucleotide polymorphisms (SNPs) associated with exposure were selected. MR Egger regression was used for the evaluation of the horizontal pleiotropy in SNPs. F-statistic reflects the strength of instrumental variables. Cochran’s Q statistic was used to investigate the heterogeneity of SNPs. The primary MR method exploring the causal association between gestational and perinatal factors and the risk of childhood obesity was inverse variance weighted (IVW). Leave-one-out analysis was employed to identify whether the MR results were affected by single SNPs. Odds ratio (OR) and 95% confidence interval (CI) were imputed.
Results: IVW indicated that birth weight was a risk factor for childhood body mass index (BMI) (OR=1.347, 95%CI: 1.212-1.498) and childhood obesity (OR=1.793, 95%CI: 1.300-2.473). Increased risk of childhood obesity was identified in mother with gestational diabetes (OR=1.059, 95%CI: 1.006-1.116). Gestational diabetes was causally related to elevated childhood BMI. Gestational diabetes was causally related to elevated risk of childhood obesity (OR=1.249, 95%CI: 1.044-1.495).
Conclusions: Birth weight and gestational diabetes was causally related to childhood BMI and childhood obesity.