Bracero 1997.

Methods	RCT. Individual women. 2‐arm study.
Participants	Inclusion criteria Women undergoing CS and at high risk of developing post‐operative infection. Criteria for high risk: > 4 pre‐operative vaginal examinations; internal fetal monitoring; obesity; ruptured membranes for > 30 minutes; meconium‐stained amniotic fluid; labour of any duration before the operation.      16 to 48 years. N = 196 but 26 excluded for protocol violations = 170 analysed. Exclusion criteria Women with hypersensitivity to penicillins or cephalosporins; those with required concomitant antibiotic therapy; or had received antibiotics during 72 hrs preceding enrolment; those in another drug study; women with immunological, renal or hepatic impairment or who had concomitant infections that might confuse the interpretation of the results.
Interventions	Intervention: cephalosporin (B2). Cefotetan. 1 g, single dose, IV, at time of cord clamping. N = 83. Comparison: penicillin (A4) combination. Ampicillin + sulbactam (0.5 g). 1 g, single dose, IV, at time of cord clamping. N = 87.
Outcomes	Treatment success; incision site infection; endometritis; UTI; febrile morbidity; peak recorded temperature; days in hospital.
Notes	Setting: Westchester County Medical Center, US. Subgroups Type of CS not defined. After cord clamping. IV administration. Single dose. Comparisons: 1 (subgroup 2); 2; 3; 4; 8. "This work was supported by a grant (89‐S‐0591, R‐0102) from The Reorig Division of Pfizer Inc."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“A computer was used to generate a list of random numbers for two groups.”
Allocation concealment (selection bias)	Low risk	“Treatment assignments were placed in numbered, sealed and opaque envelopes."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	“Neither patient nor obstetrician was informed of the antibiotic assignment. The study drugs were administered by the anaesthesiologist in the operating room immediately after the umbilical cord was clamped”
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	“Neither patient nor obstetrician was informed of the antibiotic assignment"
Incomplete outcome data (attrition bias) All outcomes	Low risk	26/196 (13%) women were excluded because of protocol violations.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	High risk	"This work was supported by a grant (89‐S‐0591, R‐0102) from The Reorig Division of Pfizer Inc." Not stopped early; no imbalance in baseline characteristics assessed on: on age; race; weight; height; BP; temperature and pulse but other aspects of bias were unclear.