It is not known which is better for intraoperative temperature protection, warming matress or preoperative oral functional drinks in elective cesarean section. We plan to conduct a non inferiority randomized trial to clarify this problem.

Inclusion Criteria:

• Women pregnant with a single fetus;
• American Society of Anesthesiologists (ASA) physical status II;
• Willingness to undergo elective cesarean delivery under combined spinal-epidural anesthesia;
• A body mass index (BMI) < 35 kg·m-2;
• A gestational age of 38-40 weeks.

Exclusion Criteria:

• Contraindications for combined spinal-epidural anesthesia;
• A diagnosis of delayed gastric emptying, hyperemesis gravidarum until late pregnancy, or consumption of drugs that affect gastrointestinal motility within 3 days before surgery;
• Preoperative body temperature >38°C or <36°C or the use of drugs that affect body temperature;
• Pregnancy combined with diabetes, hypertension, or metabolic disorders (eg, hypothyroidism or hyperthyroidism);
• Ear diseases (eg, otitis media, tympanic membrane perforation, etc) affecting measurement of ear temperature;
• Intraoperative malfunction of the warming blanket;
• Patients who were simultaneously undergoing other operations (eg, removal of uterine fibroids and ovarian cysts) or had a surgical time >1.5 hours;
• Patients with blood transfusion or autologous blood transfusion intraoperatively;
• Patients who did not receive the anesthetic specified in the protocol;
• Patients who failed to drink 125ml energy drinks before surgery.