Rehu 1980.

Methods	RCT; 3 parallel groups. Unit of randomization: individual.
Participants	Dates of data collection: September 1977‐January 1978. Setting: State Maternity Hospital, Helsinki, Finland. Inclusion criteria: all women undergoing CS. N = 128. Exclusion criteria: allergic to penicillin, clindamycin or gentamicin; emergency section.
Interventions	Intervention: penicillin: benzyl penicillin,10 MU IV; N = 46. Intervention: combination (lincosamides plus aminoglycoside): clindamycin, 500 mg IV plus gentamicin, 80 mg IM; N = 42. Comparison: placebo: vs glucose solution placebo, IV by infusion starting 30 minutes before operation and stopping 4 hrs after; N = 40. Placebo data spilt for comparison with the 2 antibiotic groups.
Outcomes	Endometritis (fever, uterine tenderness and foul‐smelling vaginal discharge); wound infection (all grades combined); hospital stay (treatment 7.7 vs 7.7 placebo; no variance given).
Notes	Data from a 4th group that consisted of patients allergic to 1 of the drugs or undergoing an emergency section have not been included. Drug class: natural penicillin or aminoglycoside‐containing combination (lincosamide (clindamycin) and aminoglycoside). Subgroups: type of CS unclear; before cord clamping. The 1st 3 groups were comparable regarding number of amnioscopic examinations, number of vaginal examination, duration of labor and duration of intrauterine monitoring.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Assigned at random". Comment: no description of sequence generation process.
Allocation concealment (selection bias)	Unclear risk	Quote: " ... in bottles containing code numbers". Comment: insufficient information to judge.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: no loss to follow‐up reported; 2 women excluded after initial randomization. ITT analysis with available data.
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to judge.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "the code was kept secret for persons performing the operations and observing the patients in the post‐operative period".. Comment: placebo‐controlled (glucose solution)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "the code was kept secret for persons .... observing the patients in the post‐operative period".
Other bias	Low risk	Comment: no other sources of bias identified.