In the remaining 58 studies not reporting the use of insulin, women with GDM had increased odds of preeclampsia (1.46; 1.21-1.78), induction of labor (1.88; 1.16-3.04), cesarean section (1.38; 1.20-1.58), and premature rupture of membranes (1.13; 1.06-1.20). This evidence concerns the gene INS and gestational diabetes.