Benigno 1986.

Study characteristics
Methods	RCT. Individual women. Multi‐centre (6 centres). 2‐arm study.
Participants	Inclusion criteria Women undergoing primary or repeat CS. N = 346 but analysed 283 Exclusion criteria Use of antimicrobial therapy within previous 7 days; sensitivity to cephalosporins or penicillin; abnormal renal or hepatic laboratory tests; intention to breastfeed within 24 hours of birth; infection at the time of enrolment.
Interventions	Intervention: 2nd generation cephalosporin (C2). Cefoxitin (C2) 6 g total. 3 IV doses of 2 g each at 4‐hour intervals starting immediately after cord clamping. N = 177 but 147 analysed. Comparator: broad spectrum penicillin (P2). Piperacillin (P2) 6 g total. 3 IV doses of 2 g each at 4‐hour intervals starting immediately after cord clamping. N = 169 but 136 analysed. Subgroups Type of CS: mixed, elective and non‐elective Generation of cephalosporin and type of penicillin: 2nd generation cephalosporin, C2; broad spectrum penicillin, P2 No primary outcome data for subgroup analyses Comparisons: 4
Outcomes	Satisfactory prophylactic response; febrile morbidity (temperature > 38 ºC x 2 occasions, 6 hours apart, not included first 24 hours post operation; wound infection).
Notes	Dates of study: not reported. Setting: women from hospitals and universities of San Francisco, Atlanta, Memphis, Los Angeles, Phoenix, New York. Additional information This study included some long‐term follow‐up. 'Unsatisfactory prophylaxis ‐ bacterial infection within 3‐10 weeks' was 11/147 with cephalosporin and 15/136 with penicillin (RR 0.68, 95% CI 0.23 to 1.43). Costs: this trial did not provide any information or comment on costs of treatment. Funding sources: not reported. Declarations of interest: not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“...a computer‐generated randomization schedule...”
Allocation concealment (selection bias)	Low risk	“...a computer‐generated randomization schedule maintained by each hospital pharmacy...”
Blinding of participants and personnel (performance bias) All outcomes	Low risk	“The investigator and his (or her) staff were blinded as to antibiotic assignment. The code was not broken by the investigator until the last patient had been evaluated for prophylactic response.”
Blinding of outcome assessment (detection bias) All outcomes	Low risk	“The investigator and his (or her) staff were blinded as to antibiotic assignment. The code was not broken by the investigator until the last patient had been evaluated for prophylactic response.”
Incomplete outcome data (attrition bias) All outcomes	High risk	Excluded after randomisation: cephalosporin group 30/177 (16.9%) and penicillin group 33/119 (19.5%). Also differential loss from 2 groups.
Selective reporting (reporting bias)	Unclear risk	Publication seemed to report on the outcomes listed in the methods section, but we did not assess trial protocol.
Other bias	Unclear risk	Study not stopped early; similar baseline characteristics for weight; height and race, but significant difference in mean age ‐ though not considered important. Other aspects of bias were unclear. No information on funding source of study.