[1] Univ Autonoma Barcelona, Hosp Univ Vall dHebron, Dept Obstet, Maternal Foetal Med Unit, Passeig Vall dHebron 119-129, Barcelona 08036, Spain
[2] Hosp Materno Infantil Canarias, Dept Obstet, Maternal Foetal Med Unit, Canary Islands, Spain
[3] Hosp Son Llatzer, Dept Obstet, Maternal Foetal Med Unit, Balearic Islands, Spain
[4] Inst Sanitari Dexeus, Dept Obstet, Maternal Foetal Med Unit, Barcelona, Spain
[5] Hosp St Joan Reus, Dept Obstet, Maternal Foetal Med Unit, Tarragona, Spain
[6] Hosp Fuenlabrada, Dept Obstet, Maternal Foetal Med Unit, Madrid, Spain