Birth weight estimates for OGDM-Insulin and OGDM-Metformin in comparison to offspring not exposed to GDM were − 117.2 g (95% CI -173.8, -60.7) and − 200.3 g (− 328.5, − 72.1) respectively, and these were changed to 161.2 g (113.9, 208.4) and 47.6 g (-58.1, 153.3) upon adjustment for gestational age at birth (Online Resource 1). This evidence concerns the gene INS and gestational diabetes.