There are no prior published reports regarding the use of a rapid serum BNP assay to evaluate cardiac function during pregnancy for women with known cardiac disease. From June 1, 2003 to May 31, 2004, the Regional Perinatal Center at SUNY Upstate Medical University provided obstetrical care and consultation for 55 patients with ICD-9 Code 648.63, cardiac disease in pregnancy. Since this is a pilot study, it is anticipated that 20 subjects for the cardiac disease cohort can be followed over the course of 1 to 2 years, along with a control cohort.