Evaluation of the Arabin cervical pessary for prevention of preterm birth in women with a twin pregnancy and short cervix (STOPPIT-2): An open-label randomised trial and updated meta-analysis - Norman, JE; Norrie, J; MacLennan, G; Cooper, D; Whyte, S; Chowdhry, S; Cunningham-Burley, S; Mei, XW; Smith, JBE; Shennan, A; Robson, SC; Thornton, S; et al. (PLoS Medicine, 2021)