1 Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, National University Hospital, Singapore; Yong Loo Lin School of Medicine, National University Hospital, Singapore.
2 Institute of Virology and Immunology, University of Bern, Switzerland; Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, University of Bern, Switzerland.
3 Perinatal Pathology Consulting, Atlanta, Georgia, USA.
4 Division of Pediatric Infectious Diseases, Department of Pediatrics, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.
5 Materno-fetal and Obstetrics Research Unit, Department Woman-Mother-Child, Lausanne University Hospital, Lausanne 1011, Switzerland. Electronic address: david.baud@chuv.ch.