Timing of administration of prophylactic antibiotics for caesarean section: a systematic review and meta-analysis

Background: Prophylactic antibiotics reduce infectious morbidity from caesarean section. The timing of their administration, however, is a matter of controversy.

Objectives: To examine maternal and neonatal infectious morbidity in women receiving preoperative prophylaxis compared with those receiving intraoperative administration.

Search strategy: Medline, Embase, Current Controlled Trials and Cochrane Central were searched from their inception dates to December 2011.

Selection criteria: Randomised controlled trials of a single dose of any antibiotic comparing preoperative with intraoperative administration were selected.

Data collection and analysis: Trial characteristics, outcomes and quality measures, based on the Cochrane tool for risk of bias, were independently extracted. The random effect model of DerSimonian and Laird to estimate relative risks (RRs) for maternal and neonatal outcomes was used.

Main results: Six trials met the inclusion criteria, reporting on 2313 women and 2345 newborns. Preoperative administration was associated with a significant 41% reduction in the rate of endometritis compared with intraoperative administration (RR 0.59; 95% confidence interval [95% CI] 0.37-0.94; I2 0%). In the preoperative group, there were nonsignificant reductions in the rates of wound infection (RR 0.71; 95% CI 0.44-1.14; I2 0%), maternal febrile morbidity (RR 0.94; 95% CI 0.46-1.95; I2 0%), neonatal sepsis (RR 0.81; 95% CI 0.47-1.41; I2 0%), neonatal septic work-up (RR 0.93; 95% CI 0.71-1.21; I2 0%) and neonatal intensive-care unit admission (RR 0.92; 95% CI 0.65-1.28; I2 0%). There were nonsignificant increases in the rates of maternal pyelonephritis (RR 1.09; 95% CI 0.49-2.43; I2 0%) and neonatal pneumonia (RR 3.36; 95% CI 0.55-20.47; I2 0%).

Conclusions: Compared with intraoperative administration, preoperative antibiotics significantly reduce the rate of endometritis. The lack of neonatal adverse effects should be cautiously interpreted given the limited power of the trials to detect such effects.