Colais et al. BMC Pregnancy and Childbirth (2018) 18:383 https://doi.org/10.1186/s12884-018-2018-4 Paola Colais, Katia Bontempi, Luigi Pinnarelli, Carlo Piscicelli, Ilenia Mappa, Danilo Fusco and Marina Davoli (Full list of author information is available...