Spong Catherine Y, Reddy Uma M, Willinger Marian
Pregnancy and Perinatology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20852, USA.
Lancet. 2011 May 14;377(9778):1635-6. doi: 10.1016/S0140-6736(11)60025-1. Epub 2011 Apr 13.