A Welsh1,2, A Henry3. 1. Royal Hospital for Women, Department of Maternal-Fetal Medicine Randwick, Sydney, New South Wales, Australia. 2. University of New South Wales, Division of Women & Children's Health, Randwick, Sydney, New South Wales, Australia. 3. Department of Obstetrics & Gynaecology, St George Hospital, Kogarah, New South Wales, Australia.