GSTM1 and gestational diabetes: Unchanged Hb level from booking to second trimester was significantly associated with GDM risk in Model 1 (AOR: 2.55; 95% CI: 1.20, 5.44; p < 0.05), Model 2 (AOR: 2.45, 95% CI: 1.13, 5.34; p < 0.05) Model 3 (AOR: 2.42; 95% CI: 1.11, 5.27; p < 0.05), and Model 4 (AOR: 2.51; 95% CI: 1.15, 5.49; p < 0.05).