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.

OBJECTIVE: The ProTWIN Trial (NTR1858) showed that, in women with a multiple pregnancy and a cervical length < 25(th) 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. METHODS: ProTWIN is a multicenter randomized trial in which 808 women with a multiple pregnancy were assigned to pessary or control. Using these data we developed a multivariable logistic model comprising treatment, cervical length, chorionicity, pregnancy history and number of fetuses, and the interaction of these variables with treatment as predictors of adverse perinatal outcome. RESULTS: Short cervix, monochorionicity and nulliparity were predictive factors for a benefit from pessary insertion. History of previous preterm birth and triplet pregnancy were predictive factors of possible harm from pessary. The model identified 35% of women as benefiting (95% CI, 32-39%), which is 10% more than using cervical length only (25%) for pessary decisions. The model had acceptable calibration. We estimated that using the model to guide the choice of pessary placement would reduce the risk of adverse perinatal outcome significantly from 13.5% when no pessary is inserted to 8.1% (absolute risk reduction, 5.4% (95% CI, 2.1-8.6%)). CONCLUSIONS: We developed and internally validated a multivariable treatment selection model, with cervical length, chorionicity, pregnancy history and number of fetuses. If externally validated, it could be used to identify women with a twin pregnancy who would benefit from a pessary, and lead to a reduction in adverse perinatal outcomes in these women. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Using vaginal Group B Streptococcus colonisation in women with preterm premature rupture of membranes to guide the decision for immediate delivery: a secondary analysis of the PPROMEXIL trials.

OBJECTIVE: To investigate whether vaginal Group B Streptococcus (GBS) colonisation or other baseline characteristics of women with preterm premature rupture of membranes (PPROM) can help in identifying subgroups of women who would benefit from immediate delivery. DESIGN: Secondary analysis of the PPROMEXIL trials. SETTING: Sixty hospitals in the Netherlands. POPULATION: Women with PPROM between 34 and 37 weeks of gestation. METHODS: Random assignment of 723 women to immediate delivery or expectant management. MAIN OUTCOME MEASURES: Early onset neonatal sepsis. RESULTS: Vaginal GBS colonisation status was the only marker which was significantly associated with the benefit of immediate delivery (P for interaction: 0.04). GBS colonisation was observed in 14% of women. The risk of early onset neonatal sepsis in GBS-positive women was high (15.2%) when they were managed expectantly but this risk was reduced to 1.8% with immediate delivery. The early onset neonatal sepsis risk was much lower in neonates of GBS-negative women: 2.6% after expectant management and 2.9% with immediate delivery. We estimated that by inducing labour only in GBS-positive women, there would be a 10.4% increase in term delivery rate, while keeping neonatal sepsis and caesarean delivery rates comparable to a strategy of labour induction for all. CONCLUSIONS: Our post hoc findings suggest that women with PROM between 34 and 37 weeks might benefit from immediate delivery if they have GBS vaginal colonisation, while in GBS-negative women labour induction could be delayed until 37 weeks.