The clinical trial concerned with selection of the suturing methods for uterine wound relating to uterine tissue oxygen saturation in cesarean section

INTERVENTION: The full thickness myometrial closure including the endometrial layer (single interrupted suture) The myometrial closure excluding the endometrial layer (single interrupted suture) CONDITION: Pregnant women over 36 weeks of gestation who will undergo the first cesarean section PRIMARY OUTCOME: To compare the tissue oxygen saturation and total hemoglobin index of uterine wound between full thickness myometrial closure including the endometrial layer and myometrial closure excluding the endometrial layer SECONDARY OUTCOME: To investigate the tissue oxygen saturation and total hemoglobin index compared between two groups as follows:; 1. Closure at 1cm pitch versus closure at 2cm pitch in single‐layer; 2. Single‐layer versus double‐layer closure of lower uterine segment incision ; 3. The edge area of uterine wound versus the center of uterine wound; 4. The lower side of uterine wound versus the upper side of uterine wound INCLUSION CRITERIA: Pregnant women over 36 weeks of gestation and who will undergo the first cesarean section