Statistical Analysis
Data analysis was conducted with RevMan version 5.4.1 and Stata version 14.0 software. Dichotomous outcomes were reported as risk ratios (RRs) with 95% confidence intervals (95% CIs). For continuous variables, data were presented as mean differences (MDs) with 95% CIs. Heterogeneity was investigated by the χ2 test andI2 statistics; if there was no significant heterogeneity (P≥0.10, I2 ≤50%), a fixed-effects model was used; if not, a random-effects model was used. Sensitivity analyses were performed for outcomes with significant heterogeneity by excluding one study at one time. Publication bias and sensitivity analysis were evaluated via Stata version 14.0 software. We performed a subgroup analysis based on the time of the first dose of antibiotic drugs.