[1] Univ Lausanne, Lausanne Univ Hosp, Materno Fetal & Obstet Res Unit, Dept Woman Mother Child, Lausanne, Switzerland
[2] Univ Calif Los Angeles, David Geffen Sch Med, Dept Pediat, Div Pediat Infect Dis, Los Angeles, CA USA
[3] Natl Univ Singapore Hosp, Dept Obstet & Gynecol, Div Maternal Fetal Med, Singapore, Singapore
[4] Natl Univ Singapore, Yong Loo Lin Sch Med, Singapore, Singapore