Prevention of preterm birth

INTERVENTION: Participants are randomly allocated to receive one of three treatments: 1. Arabin pessary: silicone cerclage pessary device sited around cervix in clinic 2. Cervical cerclage: Macdonald technique to site suture, surgically in cervical tissue. Performed in theatre under aseptic technique 3. Vaginal progesterone: single administration vaginal micronised progesterone pessary (Uterogestan) 200mg nocte pv, prescription given in clinic and collected from pharmacy CONDITION: Topic: Reproductive Health; Subtopic: Reproductive Health & Childbirth (all Subtopics); Disease: Reproductive Health & Childbirth ; Pregnancy and Childbirth ; Preterm birth PRIMARY OUTCOME: Feasibility is measured at 12 months post recruitment, with follow up until final mother and baby discharge or 6 weeks postnatal. SECONDARY OUTCOME: 1. Economic analysis is completed at 12 months post recruitment; 2. Patient and staff acceptability is measured 1‐2 months post study completion INCLUSION CRITERIA: 1. Aged 18 years or older 2. Singleton pregnancy 3. Between 16+0 – 24+6 weeks in current pregnancy 4. History of previous spontaneous preterm birth (sPTB) or premature rupture of membranes (PPROM) between 16‐33+6 AND 5. Cervical length at least <3rd centile for gestational age OR 6. History of significant cervical surgery defined as two large loop excision of the transformation zone (LLETZ) procedures or a single knife cone biopsy (KCB) where a clinical decision is made to treat the short cervix 7. Clinical equipoise as to what is the best treatment