Noyes 1998.

Methods	RCT. Individual women. 3‐arm study.
Participants	Inclusion criteria Women undergoing CS. Gravid women in labour or having had rupture of membranes for 6 hours. N = 300, but analysis on 292. Exclusion criteria < 18 years of age, known allergy to penicillin or cephalosporin antibiotics, antibiotic therapy within 72 hours prior to hospital admission, history of group B streptococcal infection, prophylactic antibiotic therapy for underlying medical illness or enhancement of fetal lung maturity, or clinical evidence of chorioamnionitis at the time of CS.
Interventions	Intervention 1: cephalosporin (B1). Cefazolin. 1 g, IV, single dose. N = 98. Intervention 2: cephalosporin (B2). Cefotetan. 1 g, IV, single dose. N = 99. Comparison: penicillin (A4) combination. Ampicillin + sulbactam. 1.5 g, IV, single dose. N = 95.
Outcomes	Endometritis.
Notes	Dates: July 1988 to November 1990. Setting: New York Hospital, university‐based, US. Subgroups Non‐elective CS. After cord clamping. IV administration. Single dose. Comparison: 1 (subgroup 2); 2; 3; 4; 6; 8. No information about funding source of study.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Prospective randomized trial”.
Allocation concealment (selection bias)	Unclear risk	No information provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	8 out of 300 women (2.7%) were excluded from the analysis.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	Unclear risk	There was insufficient information to assess other possible biases. No information about funding source of study.