We compared maternal and neonatal outcomes in women who received prophylactic
antibiotics prior to skin incision to those who received
antibiotics at cord clamp. We performed a randomized clinical trial at two sites. Eligible women included those undergoing nonemergency cesarean at 36 weeks' gestation or greater. Subjects were randomized (permuted blocks) into one of two treatments: "preoperative
antibiotics" (
cefazolin 1 g given <30 minutes prior to skin incision) or "intraoperative
antibiotics" (
cefazolin 1 g at cord clamping). Patients who reported an
allergy to
penicillin received
clindamycin 900 mg. The trial primary outcome was a composite of maternal infectious morbidities, defined as having any one of the following: (1) postoperative
fever (defined as oral temperature >38°C on two separate occasions more than 6 hours apart, after the initial 24-hour postoperative period); (2)
wound infection (defined as purulent discharge from the incision); (3)
endomyometritis (defined as fundal tenderness and
fever malodorous lochia,
fever); (4)
urinary tract infection (defined as
fever, positive urine culture). We enrolled a total of 434 subjects in this study, with 217 in each group. Overall, we found no difference in composite maternal infectious morbidity between those who received
antibiotics preoperatively and those who received
antibiotics at cord clamp (relative risk = 1.2, 95% confidence interval 0.7 to 1.5). Neonatal outcomes were also similar between the two intervention arms. The rate of suspected
sepsis was similar between the two groups. There were no cases of antibiotic resistance in the neonates. Either preoperative
antibiotic therapy or
antibiotic administration after cord clamp is a reasonable clinical method for reducing the risk of postcesarean infectious morbidity.