Witt 2011.

Methods	Randomized controlled trial.
Participants	1112 women with a fetus ≥ 37 weeks' gestation undergoing elective cesarean delivery of a fetus with reassuring fetal heart rate tracing.
Interventions	Group A: 2 g cefazolin in 100 mL saline 20‐30 minutes before incision (n = 370). Group B: 2 g cefazolin in 100 mL saline immediately after cord clamp (n = 371). Group C: 100 mL saline 20‐30 minutes before incision (n = 371).
Outcomes	Total postoperative infectious morbidity (endometritis, wound infection, UTI).
Notes	1 hospital in Vienna, Austria. 3/1/04 ‐ 1/31/10.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated permuted blocks of 5.
Allocation concealment (selection bias)	Low risk	Only the study nurse was not blinded and handed appropriate infusion bag to anesthesiologist.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Women and surgeons masked to administration schedule.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Infectious morbidity was evaluated by 2 residents who were masked to group assignments.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Protocol violations in Groups 1, 2, and 3 respectively: 12, 7, and 13. 32 women lost to follow‐ up/protocol violations/withdrawal.
Selective reporting (reporting bias)	Low risk	Prespecified outcomes.
Other bias	Low risk	No other bias evident.