We conducted overlap propensity score-weighted analyses and inverse probability-weighted analyses in parallel to compare the incidence of postpartum hemorrhage (PPH) and adverse events within 24 hours after CD, including the mean amount of lochia, the incidence of blood transfusion, shock, and additional procedures to control bleeding, and reduction in hemoglobin (Hb) levels and hematocrit (Ht) values before and after CD. The gene discussed is GSTM1; the disease is postpartum hemorrhage.