ISRCTN66445401

Trial name or title	Prevention of preterm birth in twin pregnancies ‐ “Randomised trial of progesterone versus placebo”
Methods	Multicentre, double‐blind, placebo‐controlled, randomised trial
Participants	Target number of women: 1180 Inclusion criteria: women with a twin pregnancy attending for their routine first trimester scan, 18 or over, DCDA or MCDA twin pregnancies, live fetuses at 11 ‐ 13 weeks of gestation, English‐ or Spanish‐speaking (otherwise interpreters will be used) Exclusion criteria: pregnancies complicated by major fetal abnormality identified at the 11‐13 weeks assessment, including nuchal translucency thickness > 3.5 mm, in MCDA twin pregnancies there are early signs of twin‐to‐twin transfusion syndrome (TTTS) (20% discordance in CRL and/or nuchal translucency), women who are unconscious or severely ill, those with learning difficulties, or serious mental illness, hypersensitivity to progesterone, concurrent participation in another drug trial or at any time within the previous 28 days, any other reason the clinical investigators think will prevent the potential participant from complying with the trial protocol
Interventions	Intervention: participants are required to insert a 300 mg progesterone suppository twice daily until 34 weeks’ gestation, or earlier in the event of preterm delivery Control: participants are required to insert a 300 mg placebo suppository twice daily until 34 weeks’ gestation, or earlier in the event of preterm delivery
Outcomes	Primary outcome: Incidence of spontaneous delivery before 34 weeks (238 days) of gestation Secondary outcomes: 1. The incidence of spontaneous preterm birth < 37 weeks (259 days) of gestation 2. Birthweight below the 3rd, 5th and 10th centile 3. Rate of stillbirth or neonatal death due to any cause 4. Major adverse outcomes before discharge from the hospital (IVH, RDS, retinopathy of prematurity, or NEC) 5. Need for neonatal special care (admission to a NICU, ventilation, phototherapy, treatment for proven or suspected sepsis, or blood transfusion)
Starting date	April 2016
Contact information	Dr Catalina De Paco Fetal Medicine Unit Hospital Universitario “Virgen de la Arrixaca” Murcia 30120 Spain
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