Pessary for Prevention of Preterm Birth and Perinatal Mortality in Pregnancies with a Short Cervix: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Abstract

Objective: This systematic review and meta-analysis aimed to evaluate the efficacy of cervical pessaries in preventing perinatal mortality and extreme preterm birth in pregnancies characterized by a short cervix. Methods: The analysis included data from nine randomized controlled trials (RCTs), incorporating a total of 3813 participants. These studies compared the use of cervical pessaries against standard care or other interventions in preventing preterm births in women with a short cervix, defined as less than 30 mm. The eligibility criteria for the trials included studies on asymptomatic pregnant women with a short cervix. The primary outcomes analyzed were perinatal mortality and the incidence of preterm birth before 28 weeks of gestation. Results: The results showed an imprecise effect estimate for perinatal mortality (OR = 0.93; 95% CI: 0.54 to 1.62). Similarly, the risk reduction for preterm birth before 28 weeks was also non-significant (OR = 0.76; 95% CI: 0.49 to 1.15). Substantial heterogeneity was observed among the studies (I² = 62%), suggesting variability in the study results, which could have been influenced by differences in the study design, population, and interventions. Conclusions: Although the results were statistically inconclusive and the estimates imprecise, the confidence intervals still span possible benefit and harm. Thus, while the current evidence does not support the routine use of cervical pessaries, it also does not indicate an increased risk of fetal or neonatal mortality.

Keywords: cervical pessary; perinatal mortality; preterm birth; short cervix; systematic review.

Figure 1

A PRISMA diagram. The flowchart illustrates the systematic review process. It shows the identification from the PubMed, Embase, and Cochrane databases. After the screening and removal of the duplicate reports and the title/abstract, 11 studies were reviewed in full, with 9 studies ultimately included in the analysis.

Figure 2

Forest plot of studies included in systematic review with target on perinatal mortality. Forest plot summarizing risk ratio (RR) of perinatal mortality in women using pessary versus no pessary across multiple studies. Overall effect shows inconclusive and imprecise difference (RR = 0.93; 95% CI: 0.54 to 1.62). References in order of appearance in Figure 2 [18,20,23,30,31,32,33,34,35].

Figure 3

Forest plot of included studies with target on preterm birth below 28 weeks. Forest plot presenting risk ratio (RR) for extreme preterm birth in women using pessary versus no pessary across multiple studies. Overall effect shows inconclusive and imprecise difference (RR = 0.76; 95% CI: 0.49 to 1.15). References in order of appearance in Figure 3 [18,20,23,30,31,32,33,34,35].

Figure 4

Forest plot of subgroup analysis with singleton and twins with target on preterm birth below 28 weeks. Forest plot presenting risk ratio (RR) for extreme preterm birth in singleton and twin pregnancies using pessary versus expectant management. Overall effect shows inconclusive and imprecise difference in either subgroup. References in order of appearance in Figure 4 [18,20,23,30,31,32,33,34,35].

Figure 5

A forest plot of the leave-one-out sensitivity analysis for the perinatal mortality and the use of a pessary in the RCTs included. A forest plot showing the impact of omitting individual studies on the overall risk ratio (RR) for preterm birth with pessary use. The TOPS trial exclusion shows an RR of 0.79 (95% CI: 0.44 to 1.42) for the perinatal mortality when comparing pessary use to the nonuse of a pessary. This suggests a potential reduction in mortality with this exclusion, but the confidence interval is wide, crossing 1, and the heterogeneity (I²) suggests moderate variability. References in order of appearance in Figure 5 [18,20,23,30,31,32,33,34,35].

Figure 6

A trial sequential analysis assessing the cumulative evidence for the effect of cervical pessaries on the risk of preterm birth before 28 weeks. The x-axis represents the cumulative number of participants, and the y-axis shows the Z-statistic over time. The cumulative Z-curve (blue line) did not cross the conventional boundaries (horizontal brown lines) for benefit or the futility boundaries, and the required information size (RIS) was not reached. This indicates that the meta-analysis remains underpowered to draw definitive conclusions, and further studies are needed to clarify the effect.

Figure 7

A risk of bias assessment across the five domains for the included studies. This risk of bias table evaluates several studies across five domains: the randomization process (D1), deviations from the intended intervention (D2), missing outcome data (D3), the measurement of the outcome (D4), and the selection of the reported result (D5). The judgments are represented as “Low” (green) or “Some concerns” (yellow). References in order of appearance in Figure 7 [18,20,23,30,31,32,33,34,35].