Data synthesis and analysis
The analysis was conducted using Stata16.0 software. Heterogeneity across studies was assessed using the Chi² test (significance set atP < 0.1) and the statistic ( statistic < 25% was considered a low level of heterogeneity, 25% to 50% a moderate level, and > 50% a high level). IfP > 0.1 and ≤50%, the fixed effect model was selected for statistical analysis, while P ≤ 0.1 and >50%, the random effect model was selected for statistical analysis. Subgroup analyses were performed to explore the sources of heterogeneity, and meta-regression was further conducted to examine the impact of potential covariates on the effect size. The effect size was the incidence of postpartum PTSD after traumatic birth. Then, sensitivity analysis by removing one study at a time was conducted to explore the stability of the results. Finally, publication bias was assessed by Egger’s test. For all analyses, p values < 0.05 were deemed as statistically significant.