Participants and Group Allocation
OBSTETRIC COMPLICATION
This study was approved by the Ethical Committee of Shanghai First Maternity and Infant Hospital (Ethical Committee No. KS21294, approval date: September 28, 2021). All participants provided their written informed consent before the trial. The trial was registered with the Chinese Clinical Trial Registry at chictr.org.cn (registration number, ChiCTR2100055050) on December 31, 2021.Eighty term parturients aged 18 to 40 years without any medical or obstetric complications planning for elective cesarean delivery under spinal anesthesia were included in this study. For subject randomization, the statistician employed a computer-generated list they produced before the trial started. Parturients admitted to were recruited from January, 2022, to March. Data have been reported according to the CONSORT guidelines and the enrollment flowchart is presented in Fig. 
Flowchart of patient enrollment (according to the CONSORT statement)