Mehta SH, Sokol RJ (2007). Methods of assessment for pregnancy at risk. In AH DeCherney et al., eds., Current Diagnosis and Treatment: Obstetrics and Gynecology, 10th ed., pp. 249–258. New York: McGraw-Hill.
National Institute of Child Health and Human Development (2012). High-Risk Pregnancy. Available online: http://www.nichd.nih.gov/health/topics/high_risk_pregnancy.cfm.
Seely EW, Ecker J (2008). Medical complications in pregnancy. In EG Nable, ed., ACP Medicine, section 16, chap. 9. Hamilton, ON: BC Decker.