Increased doses of vaginal progesterone for the prevention of preterm birth in twin pregnancies: a randomised controlled double-blind multicentre trial

Objective  Previous trials have shown little benefit for preventing preterm birth in twin pregnancies using 90–200 mg of daily vaginal natural progesterone. Higher doses have not been tested. Our aim was to determine the efficacy and safety of two different daily doses of vaginal natural progesterone (200 and 400 mg), compared with placebo, for preventing preterm birth in unselected twin pregnancies. Design  Randomised controlled double-blind multicentre trial (1:1:1). Setting  The study was carried out in five university centres from Valencia, Murcia and Alicante (Spain). Population  Women with dichorionic diamniotic twin pregnancies. Methods  The women self-inserted two vaginal pessaries …