There were not significant differences among two groups in terms of preoperative (11.4 ± 1.3 (g/dL) vs. 11.5 ± 1.3 (g/dL), p = 0.105) and postoperative Hb (9.9 ± 1.4 (g/dL) vs. 10.2 ± 2.8 (g/dL), p = 0.089), Hb decrease (1.5 ± 1.1 (g/dL) vs. 1.3 ± 2.6 (g/dL), p = 0.359), blood transfusion (8.6% vs. 6%, p = 0.145), placenta previa (4% vs. 2.7%, p = 0.245), abnormal palcental invasion (4.5% vs. 3%, p = 0.26), uterine rupture (0.8% vs. 0.4%, p = 0.492), cesarean hysterectomy (1.2% vs. 0.9%, p = 0.67), bladder (0.4% vs. 0.3%, p = 0.932) and bowel injury (0 vs. 0). The gene discussed is GSTM1; the disease is placenta praevia.