Beningo 1986.

Methods	RCT. Individual women. Multi‐centre (6 centres). 2‐arm study.
Participants	Inclusion criteria Women undergoing primary or repeat CS. N = 346. 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: cephalosporin (B2). Cefoxitin. 6 g total. 3 IV doses of 2 g each at 4‐hour intervals starting immediately after cord clamping. N = 177 but 147 analysed. Comparison: penicillin (A3). Piperacillin. 6 g total. 3 IV doses of 2 g each at 4‐hour intervals starting immediately after cord clamping. N = 169 but 136 analysed.
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	Setting: Women from hospitals and universities of San Francisco, Atlanta, Memphis, Los Angeles, Phoenix, New York. Subgroups Type of CS not defined. After cord clamping. IV administration. Multiple doses. Comparison 1 (subgroup 1); 7. 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). No information on funding source of study.
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 two groups.
Selective reporting (reporting bias)	Unclear risk	We did not assess trial protocol.
Other bias	Unclear risk	Study not stopped early; similar baseline characteristics for weight; height & race, but significant difference in mean age ‐ though not considered important. Other aspects of bias were unclear. No information on funding source of study.