3.3.3 Premature birth rate before 34 weeks
Eight studies were included for this analysis[9-15,17]. Given the significant heterogeneity
across studies (P =0.08, I 2=45%),
sensitivity analysis was performed to detect the source of
heterogeneity. Fichera 2019 et al. was found to be the most
influential study. After excluding this study, no significant
heterogeneity was noted (P =0.58,I 2=0%), and a fixed-effect model was used for
analysis. Results revealed that the premature birth rate before 34 weeks
in the cervical pessary group was significantly lower than that in the
cervical cerclage group (RR =0.68, 95%CI : 0.51 to 0.89,P <0.006). Sensitivity analyses did not significantly
alter the results, suggesting that the results were predominantly stable
(Figure 1-4).