Methods	Randomized, controlled trial; 2 parallel groups.
	Unit of randomization: individual.
Participants	Dates of data collection: not stated.
	Setting: Pittsburgh, Pennsylvania, US.
	Inclusion criteria: women undergoing CS after labor or rupture of membranes (method section unclear as to duration of ruptured membranes; it has been assumed that all women were in labor)
	Exclusion criteria: elective CS without labor; already receiving antibiotics; fever or other evidence of infection; allergy to penicillin or cephalosporins; requiring endocarditis prophylaxis
Interventions	Cefoxitin 2 g IV after cord clamping, and at 6 and 12 hours after initial dose (N = 196) vs matching mannitol and riboflavin placebo (N = 196)
Outcomes	Febrile morbidity (fever > 37.9°C twice at least 4 hours apart after first post-operative day); endomyometritis (fever > 38°C with uterine tenderness, maternal white blood cell count > 15000/cu mm, malodorous lochia and no apparent cause for fever); UTI; incision infection (purulent drainage with induration and tenderness); additional antibiotic therapy (treatment 26/196 vs placebo 68/190)
Notes	Increase in enterococci and decrease in Staphylococcus aureus, various streptococci, E. coli and a variety of anaerobes from infected sites in prophylactic group compared with placebo
	Class of antibiotics: second generation cephalosporin (cefamycin)
	Subgroups:
	non-elective CS; after cord clamping.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	“Randomized.”
		No further information.
Allocation concealment?	Yes	“The hospital pharmacy prepared coded vials.”
Blinding?	Yes	Double-blind, identical appearing placebo.
All outcomes
Incomplete outcome data addressed?	No	Insufficient information to judge.
All outcomes
Free of selective reporting?	Unclear	No loss to follow up reported. 14/400 women initially randomized not included in final analysis (errors in protocol, 2 allergic to penicillin after first dose given and 2, who received cefoxitin, for infusion-related reactions); insufficient data provided to perform ITT analysis
Free of other bias?	Unclear	The 2 groups were comparable regarding demographic and obstetric variables and indications for CS. There was insufficient other information which to judge
Overall low risk of bias?	Unclear	Mostly unclear.