1. Most frequent conditions in US hospitals, 2011. Vol HCUP statistical brief no. 162;Pfuntner,2013
2. World Health Organization. Trends in maternal mortality: 1990 to 2013. Estimates by WHO, UNICEF, UNFPA, The World Bank and the United Nations Population Division. Geneva: World Health Organization; 2014. Available at: http://apps.who.int/iris/bitstream/10665/112682/2/9789241507226_eng.pdf?ua=1. Accessed May 13, 2014.
3. Pregnancy-related mortality in the United States, 2006-2010;Creanga;Obstet Gynecol,2015
4. Centers for Disease Control and Prevention. Pregnancy mortality surveillance system, 2014. Available at: www.cdc.gov/reproductivehealth/MaternalInfantHealth/PMSS.html. Accessed Jan. 15, 2015.
5. Maternal morbidity during childbirth hospitalization in California;Lyndon;J Matern Fetal Neonatal Med,2012