Cervical pessaries to prevent preterm birth in women with a multiple pregnancy: a per-protocol analysis of a randomized clinical trial.

INTRODUCTION: We recently showed that a cervical pessary prevents preterm birth and reduces poor neonatal outcomes in women with a twin pregnancy and a short cervix (<38 mm). The objective of this study was to evaluate the full potential treatment effect of the pessary in the whole group and in women with a short cervix. MATERIAL AND METHODS: We performed a per-protocol analysis of a multicenter randomized controlled trial (ProTWIN trial, NTR1858) where we excluded women who were allocated to the pessary but never had it placed. Women who had the pessary removed before 36 gestational weeks and did not deliver within 7 days after removal, were excluded. Analyses were performed on all women and in those with a cervical length <38 mm. RESULTS: In 23 (6%) women the pessary was not placed. In women with a cervical length <38 mm (25th percentile) the pessary reduced poor perinatal outcome (relative risk 0.32, 95% confidence interval 0.13-0.78) and birth at <32 weeks (relative risk 0.41, 95% confidence interval 0.20-0.87). After excluding 47 (12%) women, the time to delivery was longer in the pessary group than in the control group (whole group: hazard ratio 0.68, 95% confidence interval 0.55-0.82, cervical length <38 mm: hazard ratio 0.35, 95% confidence interval 0.22-0.57). CONCLUSIONS: The analysis confirms the principal findings of the intention-to-treat analysis. Time to delivery was longer in the pessary group than in the control group when censored data were used. This implies the pessary should not be removed until labor is evident.

Indicators for Cervical Length in Twin Pregnancies.

OBJECTIVE: Cervical length (CL) is associated with the risk of preterm birth (PTB) in multiple pregnancies. However, the position of CL within the pathophysiological pathway of PTB is unclear, and it is unknown which factors are predictive for CL. This study aims to investigate whether in twin pregnancies baseline maternal and obstetrical characteristics are potential indicators for CL, to improve insight in the pathophysiological pathway of PTB. STUDY DESIGN: Secondary analysis of data on twin pregnancies and CL measurement between 16 and 22 weeks. A set of 10 potential indicators, known to be associated with an increased risk of PTB and/or which have a plausible mechanism resulting in a change of CL were selected. We used multivariable linear regression with backward selection to identify independent indicators for CL. RESULTS: A total of 1,447 women with twin pregnancies were included. Mean CL was 43.7 (±8.9) mm. In multivariable analysis, age (0.27 mm/y; 95% confidence interval [CI] 0.16 to 0.39), use of assisted reproductive technologies (ART) (-1.42 mm, 95% CI -2.6 to -0.25), and having delivered at term in a previous pregnancy (1.32 mm, 95% CI 0.25 to 2.39) were significantly associated with CL. CONCLUSION: This study shows that in twin pregnancies, age, use of ART and having delivered term in a previous pregnancy has an association with CL.

Cervical pessaries for the prevention of preterm birth: a systematic review.

Introduction. Reduction of preterm birth is a major goal in obstetric care. We performed a systematic review of randomized controlled trials and cohort studies on the effectiveness of the cervical pessary to prevent preterm birth. Methods. We searched the electronic databases of MEDLINE and Embase from inception until April 2012 to identify studies investigating treatment with a cervical pessary to prevent preterm birth. We constructed two-by-two tables for delivery before 28, 34, and 37 weeks of gestation and calculated relative risks (RRs) with 95% confidence intervals. Results. The search revealed 103 potentially eligible abstracts of which six cohort studies and four randomized controlled trials (RCTs) investigated the effectiveness of the pessary. One RCT (n = 380) demonstrated a lower delivery rate prior to 34 weeks (RR 0.24; 95% CI 0.13-0.43) in the pessary group, while another RCT (n = 108) showed no positive effect of pessary for delivery before 34 weeks (RR 1.73; 95% CI 0.43-6.88). Two older quasi randomized studies and cohort studies indicated potential effect of the pessary. Conclusions. Available randomized and nonrandomized studies indicate potential effectiveness of a cervical pessary in the prevention of preterm birth. More randomized clinical trials are needed before this device can be used in clinical practice.

Ethnic and racial disparities in the risk of preterm birth: a systematic review and meta-analysis.

OBJECTIVES: The aim of this study is to present a systematic review of available literature on the effect of maternal ethnicity (Africans/blacks, Asians, Hispanics, others) on the risk of preterm birth (PTB). STUDY DESIGN: Studies investigating ethnicity (or race) as a risk factor for PTB were included if performing adjustments for confounders. A meta-analysis was performed, and data were synthesized using a random effects model. RESULTS: Forty-five studies met the inclusion criteria. Black ethnicity was associated with an increased risk of PTB when compared with whites (range of adjusted odds ratios [ORs] 0.6 to 2.8, pooled OR 2.0; 95% confidence interval [CI] 1.8 to 2.2). For Asian ethnicity, there was no significant association (range of adjusted ORs 0.6 to 2.3). For Hispanic ethnicity, there also was no significant association (range of adjusted ORs 0.7 to 1.5). CONCLUSIONS: Ethnic disparities in the risk of PTB were clearly pronounced among black women. Future research should focus on preventative strategies for ethnic groups at high risk for PTB. Information on ethnic disparities in risk of PTB-related neonatal morbidity and mortality is lacking and is also a topic of interest for future research.