Methods	RCT; 2 parallel groups.
	Unit of randomization: individual.
Participants	Dates of data collection: November 1975-June 1976.
	Setting: Medical University Hospital of South Carolina;
	Inclusion criteria: all women undergoing CS (51/97 not in labor; 61/97 without ruptured membranes)
	Exclusion criteria: signs of infection, allergy to penicillin or cephalosporin, antibiotics within 2 weeks; lack of consent
Interventions	Cefazolin 1 g IV pre-operatively and at 2 and 8 hours post-operatively (N = 48) vs similar volume of placebo (N = 49)
Outcomes	Febrile morbidity (> 100.3oF twice on any of first 10 postpartum days after the first) ; endometritis (fever and uterine tenderness, or fever and pathogen from endometrium without other cause); UTI (fever or positive culture and symptoms); wound infection (fever, cellulitis and/or exudate)
Notes	Aerobic isolates unchanged, fewer anaerobes in patients given placebo; most pathogens isolated were resistant to cefazolin whether treatment or placebo given.
	There were 2 episodes of septicemia (both in placebo group).
	Class of antibiotic: first generation cephalosporin.
	Subgroups: both elective and non-elective CS; before cord clamping.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	‘Random allocation.’
		No additional information.
Allocation concealment?	Unclear	No information provided.
Blinding?	Unclear	“A similar volume of placebo” was administered to the control group
All outcomes		No additional information.
Incomplete outcome data addressed?	No	No loss to follow up reported.
All outcomes		6 women initially randomized not included in analysis (non-adherence or noninfec-tious complications)
		ITT analysis not performed; could not re-include data.
Free of selective reporting?	Unclear	Insufficient information to judge.
Free of other bias?	Unclear	The 2 groups were comparable regarding race, age and type of CS. There was insufficient other information which to judge
Overall low risk of bias?	Unclear	Mostly unclear.