About the Authors
Institute of Reproductive and Developmental Biology, Imperial College London, and Centre for Fetal Care, Queen Charlotte's and Chelsea Hospital, London, United Kingdom
Perinatal Pathology Unit, Department of Histopathology, Hammersmith Hospital, London, United Kingdom
Nicholas Fisk is on the editorial board of PLoS Medicine.
LC and NMF designed the study. OB, LP, PG, and NMF acquired data. OB, HC, LC, and NMF analyzed the data. OB, LP, PG, HC, LC, and NMF contributed to writing the paper.