Wang 2011.

Methods	RCT, Fourth Hospital of Suzhou University, China.
Participants	300 nulliparous women undergoing elective CS under combined epidural and spinal anaesthesia were randomly divided into chewing‐gum group (150) and control group (150). Inclusion criteria: "first baby, ability to chew, intraoperative epidural anaesthesia plus spinal surgery, use of patient‐controlled analgesia pump". Exclusion criteria: "severe pregnancy‐induced hypertension, pre‐eclampsia or eclampsia, intraoperative intraperitoneal adhesions intraoperative complications, bleeding, surgical time > 2 hours, postoperative fever, need blood transfusion and reoperation". 34 women excluded in CS group (22.7%) and 33 (22%) in control group due to complications (e.g. transfusion, fever, adhesions, surgery > 2 hours), leaving 233 women in analyses. Mean age: 25.9 ± 5.0 years (intervention group), 26.7 ± 4.2 years (control group).
Interventions	Intervention group (N = 116): chewed 1 xylitol sugar‐free gum for 15 min at 2‐h intervals, from 2 h after surgery during the day time until first flatus. Time spent chewing gum > 60 min/d, based on mean time to first passage of flatus. Control group (N = 117): no food/beverage; water or liquid feed was provided after first bowel sound (conventional feeding).
Outcomes	Time to first flatus, time to first bowel sounds. Additional outcome: motilin levels in peripheral blood samples after CS.
Notes	No study protocol available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Insufficient information: "...were randomly divided into chewing gum group (150) and control group (150)".
Allocation concealment (selection bias)	Unclear risk	No information available.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The nature of intervention did not allow blinding of participants and personnel.
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Participants were unable to be adequately blinded in relation to passage of flatus.
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	No information on blinding of assessors evaluating time to first bowel sounds.
Incomplete outcome data (attrition bias) All outcomes	High risk	Losses balanced but higher than 20% in both groups: 22.7% and 22% in intervention and control groups, respectively.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes proposed in Methods were reported in Results. No study protocol available.
Other bias	Unclear risk	No information available.