Postoperative analgesia management
pain
All patients were connected to an intravenous patient-controlled analgesia (PCA, product model: ZZB-150) infusion device to receive opioid for postoperative analgesia. The PCA device was configured by a uniform formula with 100ug of sufentanil (Yichang Renfu Pharmaceutical, China; lot no.: H20054171), 10 mg of dizocine (Yangtze River Pharmaceutical Group Co., Ltd., China; Lot No.H20080329), 5 mg of toltestrone and 100ml of saline) set to a deliver a 0.6ml/10kg bolus with a lock-out time of 10 min. The PCA device was pressed when the maternal resting pain VAS score was ≥ 4.