1. Prevalence of obesity in the United States, 2009-2010;Ogden;NCHS Data Brief.,2012
2. Massive maternal obesity and perioperative cesarean morbidity;Perlow;Am J Obstet Gynecol,1994
3. Standards of obstetric-gynecologic services;American College of Obstetricians and Gynecologists,1989
4. Guidelines for perinatal care;American Academy of Pediatrics,2007
5. Report of a joint working group: organisational standards for maternity services;Royal College of Obstetricians and Gynaecologists,1995