This study aims to determine whether the Arabin cervical pessary prevents preterm birth in women with a twin pregnancy and a short cervix.

STOPPIT-2 is a multicentre open label randomised controlled trial of the Arabin pessary (CE marked Device) versus Standard treatment in women with twin pregnancy. The study is in two phases - a SCREENING phase, in which women with a short cervix (cervical length of ( less or equal to 35mm) will be identified, and a TREATMENT phase, in which women with a short cervix will be randomised to treatment with Arabin pessary or Standard treatment. Women will be seen in the antenatal clinic setting.

An internal pilot phase will take place, with ten interviews being conducted with pregnant women to explore the acceptability of proposed methods of recruitment, their information requirements, their views of the consent and randomisation processes, and the delivery of the intervention, including the screening component. The interviews will also explore their understanding and expectations of trial participation. The findings of this pilot phase will feed into the next phase of the trial and support the design of the interview guides for the main nested qualitative study.

This pilot phase is separate from the main study. Later on we will ask both women and healthcare professionals about their experiences of the study, via questionnaires and face-to-face interviews.

Inclusion Criteria:

• Women presenting with twin pregnancy (monochorionic or dichorionic)
• Women with gestation established by scan at ≤16 weeks according to NICE guidelines.
• Women aged 16 years or older
• Women wishing to participate in both the SCREENING and RANDOMISATION phase of the study

Exclusion Criteria:

• Women unable to give written informed consent
• Women with known significant congenital structural or chromosomal fetal anomaly at the time of inclusion
• Women with existing or planned cervical cerclage in the current pregnancy
• Women who with existing or planned (prior to 20+6 weeks gestation) treatment for twin to twin transfusion syndrome in the current pregnancy
• Women with suspected or proven rupture of the fetal membranes at the time of recruitment
• Women with singleton pregnancy or higher order multiple pregnancies
• Women with known sensitivity, contraindication or intolerance to silicone
• Women involved in a clinical trial of an investigational medicinal product (CTIMP)

to be confirmed