Fan 2019.

Study characteristics
Methods	Prospective randomiSed double‐blind controlled study
Participants	Setting: Affiliated Obstetrics and Gynecology Hospital of Nanjing Medical University, China from October 2012 to December 2017 Sample size: N=3000 Inclusion criteria: singleton, spontaneous labor, participants who requesting epidural labor analgesia, age from 20 to 45 years, gestation week from 37 to 41, nulliparous, cervical dilation from 1 to 3 cm. Exclusion criteria: contraindications for epidural analgesia, a baseline temperature of ≥ 37.5 °C, allergic to opioids and/or local anaesthetics, failed to perform epidural catheterization, organic dysfunction, those who were not willing to or could not finish the whole study at any time, unable to perform analgesia evaluation, using or used in the past 14 days of the monoamine oxidase inhibitors, alcohol addicts or narcotic dependent patients, subjects with a non vertex presentation or scheduled  induction of labor, multiple pregnancy, ASA physical status of 3 or higher, height less than 150 cm or more than 170 cm, morbid obesity (BMI more than 35), high‐risk pregnancy (gestational diabetes mellitus, gestational hypertension, placenta previa, placental abruption, preeclampsia).
Interventions	Group PIEB (n=1454) parturients received 10 mL of 0.08% ropivacaine with sufentanil 0.4 µg/mL hourly. Group CEI (n=1411) parturients received 10 mL of 0.08% ropivacaine with sufentanil 0.4 µg/mL hourly.
Outcomes	Primary outcome: incidence of maternal fever (>38C)   Secondary outcomes 1. Sensory levels to cold 2. Pain scores 3. Motor block 4. Maternal satisfaction 5. Duration of epidural analgesia 6. Mode of delivery 7. APGAR scores 8. Number of epidural boluses 9. Medication consumption
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote:"Random numbers were generated by computer, and then they were sequentially sealed in the envelopes for grouping."
Allocation concealment (selection bias)	Unclear risk	Allocation via sealed envelopes, but it was not stated that the envelopes were opaque: Quote:"...sequentially sealed in the envelopes for grouping..."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants were blinded: Quote:"study investigators who observed, assessed, and collected the clinical data, obstetricians, midwifes, and the participants were blinded to group assignment."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome assessors were blinded: Quote: "study investigators who observed, assessed, and collected the clinical data, obstetricians, midwifes, and the participants were blinded to group assignment."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition rate of 4.5%: CEI: 89/1500 and PIEB: 46/1500 lost to follow‐up (4.5%)
Selective reporting (reporting bias)	Low risk	All a priori outcomes reported
Other bias	Low risk	Sample size calculation provided