Shennan Andrew H, Redman Christopher, Cooper Carol, Milne Fiona
Maternal and Fetal Research Unit, St Thomas' Hospital, King's College London, London SE1 7EH, UK.
Lancet. 2012 May 5;379(9827):1686-7. doi: 10.1016/S0140-6736(11)60785-X. Epub 2011 Dec 14.