Sophie Liem

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.

Prospective risk of stillbirth and neonatal complications in twin pregnancies: systematic review and meta-analysis

Objective To determine the risks of stillbirth and neonatal complications by gestational age in uncomplicated monochorionic and dichorionic twin pregnancies. Design Systematic review and meta-analysis. Data sources Medline, Embase, and Cochrane databases (until December 2015). Review methods Databases were searched without language restrictions for studies of women with uncomplicated twin pregnancies that reported rates of stillbirth and neonatal outcomes at various gestational ages. Pregnancies with unclear chorionicity, monoamnionicity, and twin to twin transfusion syndrome were excluded. Meta-analyses of observational studies and cohorts nested within randomised studies were undertaken. Prospective risk of stillbirth was computed for each study at a given week of gestation and compared with the risk of neonatal death among deliveries in the same week. Gestational age specific differences in risk were estimated for stillbirths and neonatal deaths in monochorionic and dichorionic twin pregnancies after 34 weeks’ gestation. Results 32 studies (29 685 dichorionic, 5486 monochorionic pregnancies) were included. In dichorionic twin pregnancies beyond 34 weeks (15 studies, 17 830 pregnancies), the prospective weekly risk of stillbirths from expectant management and the risk of neonatal death from delivery were balanced at 37 weeks’ gestation (risk difference 1.2/1000, 95% confidence interval −1.3 to 3.6; I2=0%). Delay in delivery by a week (to 38 weeks) led to an additional 8.8 perinatal deaths per 1000 pregnancies (95% confidence interval 3.6 to 14.0/1000; I2=0%) compared with the previous week. In monochorionic pregnancies beyond 34 weeks (13 studies, 2149 pregnancies), there was a trend towards an increase in stillbirths compared with neonatal deaths after 36 weeks, with an additional 2.5 per 1000 perinatal deaths, which was not significant (−12.4 to 17.4/1000; I2=0%). The rates of neonatal morbidity showed a consistent reduction with increasing gestational age in monochorionic and dichorionic pregnancies, and admission to the neonatal intensive care unit was the commonest neonatal complication. The actual risk of stillbirth near term might be higher than reported estimates because of the policy of planned delivery in twin pregnancies. Conclusions To minimise perinatal deaths, in uncomplicated dichorionic twin pregnancies delivery should be considered at 37 weeks’ gestation; in monochorionic pregnancies delivery should be considered at 36 weeks. Systematic review registration PROSPERO CRD42014007538.

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.

Economic analysis of use of pessary to prevent preterm birth in women with multiple pregnancy (ProTWIN trial)

To assess the cost‐effectiveness of a cervical pessary to prevent preterm delivery in women with a multiple pregnancy.

Cervical length measurement for the prediction of preterm birth in symptomatic women with a twin pregnancy: a systematic review and meta-analysis

Objective. The aim of this study was to assess whether cervical length measurement (CL) could predict preterm birth (PTB) in symptomatic women with a twin pregnancy. Methods. We searched MEDLINE and EMBASE to identify studies investigating the accuracy of CL measurement in predicting PTB in symptomatic women with a twin pregnancy. We extracted data to construct two-by-two tables and used bivariate meta-analysis to generate point estimates of sensitivity and specificity. Results. Five studies (N = 226) were included. Variation in definition of PTB and cut-off points for CL was strong. One study investigated delivery within seven days, demonstrating a sensitivity of 1.0 (95% CI: 0.83–1.0) and a specificity of 0.31 (95% CI 0.2–0.43) for a CL cutoff at 25 mm. Three studies reported on predicting PTB < 37 weeks at a CL cutoff of 30 mm, with sROC point estimates of 0.76 (95% CI: 0.66 to 0.84) and 0.37 (95% CI: 0.21 to 0.56) for sensitivity and specificity, respectively. For preterm birth <34 weeks, no pooled estimates could be estimated since only 2 studies with large heterogeneity were identified. Conclusions. There is limited evidence on the accuracy of cervical length measurement testing the prediction of preterm birth in symptomatic women with a twin pregnancy, especially on the most important outcome, that is, delivery within 7 days.

A multivariable model to guide the decision for pessary placement to prevent preterm birth in women with a multiple pregnancy: a secondary analysis of the ProTWIN trial.

The ProTWIN Trial (NTR1858) showed that, in women with a multiple pregnancy and a cervical length < 25th percentile (38 mm), prophylactic use of a cervical pessary reduced the risk of adverse perinatal outcome. We investigated whether other maternal or pregnancy characteristics collected at baseline can improve identification of women most likely to benefit from pessary placement.

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

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.

Second-trimester cervical length as risk indicator for Cesarean delivery in women with twin pregnancy

To determine whether second‐trimester cervical length (CL) in women with a twin pregnancy is associated with the risk of emergency Cesarean section.

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.