Background: The single most important risk factor for postpartum maternal infection is cesarean section. Routine prophylaxis with antibiotics may reduce this risk and should be assessed in terms of benefits and harms.
Objectives: To assess the effects of prophylactic antibiotics compared with no prophylactic antibiotics on infectious complications in women undergoing cesarean section.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2009).
Selection criteria: Randomized controlled trials (RCTs) and quasi-RCTs comparing the effects of prophylactic antibiotics versus no treatment in women undergoing cesarean section.
Data collection and analysis: Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction.
Main results: We identified 86 studies involving over 13,000 women. Prophylactic antibiotics in women undergoing cesarean section substantially reduced the incidence of febrile morbidity (average risk ratio (RR) 0.45; 95% confidence interval (CI) 0.39 to 0.51, 50 studies, 8141 women), wound infection (average RR 0.39; 95% CI 0.32 to 0.48, 77 studies, 11,961 women), endometritis (RR 0.38; 95% CI 0.34 to 0.42, 79 studies, 12,142 women) and serious maternal infectious complications (RR 0.31; 95% CI 0.19 to 0.48, 31 studies, 5047 women). No conclusions can be made about other maternal adverse effects from these studies (RR 2.43; 95% CI 1.00 to 5.90, 13 studies, 2131 women). None of the 86 studies reported infant adverse outcomes and in particular there was no assessment of infant oral thrush. There was no systematic collection of data on bacterial drug resistance. The findings were similar whether the cesarean section was elective or non elective, and whether the antibiotic was given before or after umbilical cord clamping. Overall, the methodological quality of the trials was unclear and in only a few studies was it obvious that potential other sources of bias had been adequately addressed.
Authors' conclusions: Endometritis was reduced by two thirds to three quarters and a decrease in wound infection was also identified. However, there was incomplete information collected about potential adverse effects, including the effect of antibiotics on the baby, making the assessment of overall benefits and harms complicated. Prophylactic antibiotics given to all women undergoing elective or non-elective cesarean section is clearly beneficial for women but there is uncertainty about the consequences for the baby.