Duff 1982.

Methods	Randomized placebo‐controlled trial; 2 parallel groups. Unit of randomization: individual.
Participants	Dates of data collection: January 1970 to June 1980. Setting: Washington, DC. US. Inclusion criteria: women undergoing CS who were not in labor and did not have ruptured membranes (elective). N = 82.
Interventions	Intervention: ampicillin 1 g 30 min prior to surgery and at 4 and 8 hrs post‐operatively; N = 42. Comparison: placebo: placebo solution; N = 40.
Outcomes	Febrile morbidity (> 100.4 oF twice 6 hrs apart after the 1st 24 hrs); endomyometritis (fever, uterine and adnexal tenderness, purulent lochia); UTI; wound infection (induration, erythema and warmth with purulent drainage); need for antibiotics (treatment 1/42 vs placebo 6/40); maternal hospital stay (4.3 vs 4.6; no variance given).
Notes	No life‐threatening infection related complications nor bacteremic episodes in either group. Class of antibiotic: aminopenicillin (ampicillin). Subgroups: elective CS; before cord clamping. The 2 groups were comparable regarding age, race, gravidity, parity and socioeconomic status.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: randomized; no description of sequence generation process.
Allocation concealment (selection bias)	Unclear risk	Comment: no information was provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no loss to follow‐up; no participant excluded; ITT analysis.
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to judge.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "double‐blind" .... "placebo solution".
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Comment: insufficient information to judge.
Other bias	Low risk	Comment: no other sources of bias identified.