Stage 1982.

Methods	Randomized, placebo‐controlled trial; 2 parallel groups (2:1 active:placebo randomization). Unit of randomization: individual. Part of a larger study looking at prophylaxis also in gynecologic surgery.
Participants	Dates of data collection: July 1976 to June 1978. Setting: 14 US centers. Inclusion criteria: all women undergoing CS (46% in labor). N = 199. Exclusion criteria: infection, allergy to penicillin or cephalosporins.
Interventions	Intervention: 1st generation cephalosporin: cephradine 1 g IV; N = 133. Comparison: placebo: placebo; N = 66. Within 1 hr prior to surgery, repeated at 4 hrs.
Outcomes	Febrile morbidity (oral temperature > 37.7oC twice 4 hrs apart, after 1st 48 hrs); endometritis (uterine tenderness, fever and purulent discharge), wound infection (increased local tenderness, redness or swelling); UTI (positive culture); maternal length of stay (treatment 5.8 days vs placebo 7.57 days; P < 0.05, variance not given).
Notes	Class of antibiotic: 1st generation cephalosporin. Subgroups: type of CS undefined; before cord clamping. The 2 groups were comparable regarding age and other risk factors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Randomly allocated". Comment: no description of sequence generation process.
Allocation concealment (selection bias)	Unclear risk	Comment: investigator provided with Individually. randomized block of patient numbers.
Incomplete outcome data (attrition bias) All outcomes	High risk	Comment: dropouts in CS women not stated (overall: 11/319 from treated group, 8/172 from placebo group. As‐treated analysis performed.
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to judge.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Comment: placebo‐controlled; patients and investigators blind to allocation throughout the study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: probably outcome assessment was blinded.
Other bias	Low risk	Comment: no other sources of bias identified.