Figure 1
Flowchart of the participant recruitment and case–control selection.1Clinical information of the participants was acquired from antenatal and postnatal care record retrospection, including all maternal gestational complications and neonatal disorders (Additional file 1: Table S2). 2GDM and non-GDM mothers were diagnosed during the 24 to 28th gestational week. GDM cases were selected out through antenatal care record retrospection. 3Apparently healthy mothers without any recorded gestational complication were selected out from the 1193 non-GDM mothers (i.e., any complication potentially related to GDM was excluded), so the final controls had no GDM risk. 4Complete mother-newborn clinical information includes: A mother’s basic clinical characteristics (i.e. age, pre-pregnant BMI, gestational age, gravidity, parity, mode of delivery), gestational complications, history of drinking and smoking during pregnancy, history of macrosomic infant delivery, history of diabetes or obesity of herself and her spouse, and her newborn’s sex, birth weight and neonatal disorders. 5Most clinical information of those 137 mothers was available, except that 36 of 137 cases missed the maternal age or pre-pregnant BMI information. Metals exposure data of all 137 samples were included in the final statistical analysis.