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ProTWIN Trial


Pessaries in multiple pregnancy as a prevention of preterm birth


Go to the ProTWIN website

To investigate the hypothesis that prophylactic use of a cervical pessary will be effective in the prevention of preterm delivery and the neonatal mortality and morbidity resulting from preterm delivery in multiple pregnancy. We will evaluate the costs and effects of this intervention.

Study design
Multicenter randomised study.

Study population
All women presenting with a multiple pregnancy (monochorionic and bichorionic) between 12 and 20 weeks of gestation are eligible for the study.

Eligible women will be randomly allocated to receive either a pessary or no treatment.

Treatment group: The cervical pessary will be inserted any time between 12 and 20 weeks and continued till delivery or 36 weeks gestation, whichever comes first.

Control group: No treatment for cervical incompetence will be given.


Outcome measures

Primary outcomes

The main outcome parameter is the composite morbidity rate of children in the

two groups. This composite morbidity rate contains the following variables: severe Respiratory Distress Syndrome (RDS), Broncho Pulmonal Dysplasia (BPD), Intraventricular Haemorrhage II B or worse, Necrotizing Enterocolitis (NEC), proven sepsis and death before discharge from the nursery . They will be measured untill 10 weeks after the expected term date.


Secondary outcomes

Secondary outcome measures are time to delivery, preterm birth rate before 32 and 37 weeks, days of admission in neonatal intensive care unit, maternal morbidity, maternal admission days for preterm labour and costs.

Power/data analysis
The effectiveness of a cervical pessary versus no treatment will be assessed by calculating relative risks and 95% confidence intervals. Assuming a decrease of the incidence of bad neonatal outcome from 7.2 % without to 3.9% with a cervical pessary, using a two-sided test with an alpha of 0.05 and a power of 0.80 we need 330 women in the control group and 330 in the intervention group (660 women in total).

Time schedule
Duration of the study will be 48 months. We will need a run-in period of three months for the study set up. Thirty-eight months for inclusion of the required number of cases. Seven months for follow-up data collection and report of results.


Dr. D.J. Bekedam, gynaecologist, OLVG Amsterdam

Dr. B.W. Mol, gynaecologist, AMC Amsterdam

ZonMw - www.zonmw.nl



Drs. S.M.S. Liem, research doctor, OLVG Amsterdam, ProTwin@studies-obsgyn.nl