The demographic characterizations of the parturients in the two groups were comparable in terms of age, ASA physical status, weight, height, pregnant week, smoking history, alcohol drinking history, gestational weight gain, hypertensive disorders of pregnancy, gestational diabetes, surgery duration, the upper level of sensory block, the volume of anesthetic solution, the dose of oxytocin and the total volume of blood loss (P > 0.05, Table 1). This evidence concerns the gene OXT and gestational diabetes.