Methods	Randomized placebo-controlled trial; 2 parallel groups.
	Unit of randomization: individual.
Participants	Dates of data collection: January 1975-January 1977.
	Setting: Los Angeles County-University of Southern California Medical Center, Los Angeles, California, US, 87% Hispanic or Black
	Inclusion criteria: women in labor with ruptured membranes who underwent internal fetal monitoring (classified as non-elective)
	Exclusion: fever, other antibiotic use, penicillin allergy.
Interventions	Cefazolin 1 g IV after the cord was clamped and at 4-6 hours and 10-12 hours postoperatively (N = 48) vs placebo (N = 45)
Outcomes	Standard temperature morbidity, endomyometritis, abdominal wound infection, urinary infections (no definitions provided for any outcomes)
Notes	2 women were said to develop a serious infection: 1 (cefazolin group) developed septic thrombophlebitis and is included as a serious outcome; the other (placebo group) was treated with antibiotics for prolonged fever (judged not to be a serious outcome for this review)
	Class of antibiotic: first generation cephalosporin.
	Subgroups: non-elective CS; after cord clamping.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	“Randomized to numbered packages.” No further information.
Allocation concealment?	Yes	“… the agents having been randomized to numbered packages by the pharmacy department.”
Blinding?	Yes	Double blind study, placebo controlled; similar quantity of placebo given
All outcomes
		The physician caring for the patient did not know which agent his patient received
Incomplete outcome data addressed?	Unclear	No loss to follow up reported.
All outcomes		7 women initially randomized not included in final analysis because they did not meet all the criteria (allocated group unknown) ITT analysis not performed.
Free of selective reporting?	Unclear	Insufficient information to judge.
Free of other bias?	Unclear	The 2 patient groups reported as similar. Insufficient information overall
Overall low risk of bias?	Unclear	Mostly unclear.