However, in the two articles containing 400 GDM patients and 411 controls (24, 25), it was found that the difference of the expression levels of GDF-15 protein in the middle pregancy was not significant between GDM patients and non-GDM pregnant women, with SMD and 95%CI of 0.39 (-0.12, 0.91) (Supplementary Figure S4). The gene discussed is GDF15; the disease is gestational diabetes.