[1] St Georges Univ Hosp NHS Fdn Trust, Fetal Med Unit, London, England
[2] Univ Study Parma, Dept Med & Surg, Obstet & Gynaecol Unit, Parma, Italy
[3] Ctr Hospitalier Univ Liege, Dept Obstet & Gynecol, Liege, Belgium
[4] Univ Pavia, Dept Med & Surg, Obstet & Gynaecol Unit, Pavia, Italy
[5] Univ Brescia, Dept Med & Surg, Obstet & Gynaecol Unit, Brescia, Italy
[6] St Georges Univ London, Mol & Clin Sci Res Inst, Vasc Biol Res Ctr, London, England
[7] St Georges Univ Hosp NHS Fdn Trust, Dept Obstet & Gynaecol, Fetal Med Unit, Blackshaw Rd, London SW17 0QT, England