Ledari 2012.

Methods	A single‐blind RCT. Study conducted in 1 hospital, in Babol, Iran.
Participants	110 eligible participants enrolled but 10 excluded because "the surgeon considered them inadequate for the study". Data provided for 100 women. Both nulliparas and multiparas were included, no information on proportion of nulliparas or of participants with a previous CS, most CS were elective (86%). Anaesthesia: spinal. Inclusion criteria: candidates for CS with local anaesthesia. Exclusion criteria: "women with history of drug consumption, especially opioids, water and electrolyte disturbances, pancreatitis or peritonitis, history of abdominal surgery except cesarean section, postoperative complications, inability to chew gum, diabetes, pre‐eclampsia, prolonged rupture of membranes, hypothyroidism, muscular and neurological disorders". Mean age: 27.9 (± 6.4) and 28.5 (± 6.2) years in gum and control groups, respectively. Mean number of pregnancies: 1.1 (1.0) and 2.1 (1.2) in gum and control groups, respectively.
Interventions	Intervention group (N = 50): "... chewed sugar‐free gum for at least one hour, three times daily starting 6 hours after surgery (after recovery from anesthesia) until being discharged. Commercially available sugar‐free gum (Wrigley Company, Poland) was used...". Total chewing time = 180 min/d. Control group (N = 50): conventional feeding protocol (oral intake only after at least 2 of the following: bowel sounds, feeling of hunger or passage of flatus).
Outcomes	First bowel sounds, first passage of flatus, first defecation, tolerance to gum. Additional outcomes: first feeling of hunger; postoperative complications.
Notes	A total of 110 women were enrolled, but the available data for outcomes are 100 women. This study has 3 publications, including 1 that presents only the results of the nulliparas. IRCT201008093902N2: (see deviations from protocol in Other risk of bias).
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"All enrolled women were allocated using a computer‐generated random sequence from a statistics program."
Allocation concealment (selection bias)	Unclear risk	No information available
Blinding of participants and personnel (performance bias) All outcomes	High risk	The nature of the study did not allow blinding.
Blinding of outcome assessment (detection bias) Subjective outcomes	High risk	Participants were unable to be adequately blinded in relation to passage of flatus or stool or tolerance to gum.
Blinding of outcome assessment (detection bias) Objective outcomes	Unclear risk	No information on blinding of outcome assessors for auscultation of bowel sounds.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Rate of dropouts = 9.1%: 110 women were enrolled, but the available data for outcomes are from 100 women. No information on the number of dropouts per group.
Selective reporting (reporting bias)	High risk	Rate of complications pre‐specified in Methods but not reported in Results.
Other bias	High risk	Additional deviations from protocol: only elective CS were to be included, duration of gum chewing session was planned as 15 minutes (not 60 minutes) per session, initiation of gum chewing was supposed to occur immediately after surgery (not 6 hours after); in published paper the authors added a new outcome in Methods (complications) but did not report it in Results.