Methods	RCT; 2 parallel groups.
	Unit of randomization: individual.
Participants	Dates of data collection: July 1978-October 1980.
	Setting: Brigham and Women’s Hospital, Boston, Massachusetts, US
	Inclusion criteria: all women undergoing CS (other than repeat section); criteria do not correspond with our definition of non-elective
	Exclusion: active infection, fever, membranes ruptured > 36 hours, antibiotic therapy within 2 weeks, renal disease, allergy to penicillin or cephalosporin
Interventions	Cefazolin 2 g after cord clamped (N = 146) and at 4 and 8 hours after first dose vs matching placebo (N = 132)
Outcomes	Fever (oral temperature > 100.3 degrees Fahrenheit on any of 2 of first 10 post-operative days); UTI, wound infection (only pus-draining included in outcome of wound infection); endometritis (fever, tenderness on pelvic examination, abnormal discharge) ; pelvic abscess; septic pelvic thrombophlebitis, bacteraemia; subsequent antibiotic use (23% for placebo vs 12% for treatment)
Notes	Outcome of fever and minor wound infection combined (11/146 for treatment vs 13/ 132 for placebo).
	4 episodes of bacteraemia, all in placebo group.
	1 episode of rash and 1 episode of phlebitis reported in treatment group vs none in control.
	Data collected at 6 weeks on 259/266 patients; 35% of infections diagnosed after discharge
	Class of antibiotic: first generation cephalosporin.
	Subgroups:
	type CS undefined; after cord clamping.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	“Randomly allocated.”
		No further information.
Allocation concealment?	Unclear	No information provided.
Blinding?	Yes	Double blind; placebo-controlled.
All outcomes		“Participants, their physicians and all investigators were unaware of the assignment throughout the study.”
Incomplete outcome data addressed?	Unclear	12 participants withdrawn (8 treatment, 4 placebo) and started on therapeutic antibiotics by the surgeon because the operation had been prolonged or was complicated or the preoperative specimen of urine disclosed significant bacteriuria Results on participants excluded could not be re-included in ITT analysis
All outcomes
Free of selective reporting?	Unclear	Insufficient information to judge.
Free of other bias?	Unclear	The 2 groups were comparable regarding age, body mass index, proportion on private service, etc. There was insufficient other information which to judge
Overall low risk of bias?	Unclear	Mostly unclear.