Regarding characteristics according to center of enrollment (Additional file 1: Table S1), there were some differences in baseline maternal characteristics; however, except for preeclampsia rates (HCPA n = 69 (25.7%) vs. HNSC n = 128 (39.3%), p = 0.001) and insulin use at delivery (HCPA n = 244 (88.1%) vs. HNSC 267 (81.2%), p = 0.026), all other maternal and neonatal outcomes were similar. Here, INS is linked to preeclampsia.