"Cervical pessaries for prevention of preterm birth in women with a multiple pregnancy (ProTWIN): a multicentre, open-label randomised controlled trial"
Lancet Aug 5
http://www.lancet.com/journals/lancet/article/PIIS0140-6736(13)61408-7/fulltext
"Interpretation

In unselected women with a multiple pregnancy, prophylactic use of a cervical pessary does not reduce poor perinatal outcome."