Maternal cardiac disease complicates approximately 2 percent of pregnancies and is the leading cause of non-obstetrical maternal death. Evaluating cardiac function and dysfunction is a complex process requiring skilled clinicians and technology such as ECG, long-term monitoring, and echocardiography. A fast, easily obtained blood test for B-type natriuretic peptide (BNP) has been developed that can give evidence for heart muscle stretch and dysfunction among adults with suspected congestive heart failure. Preliminary experience indicates that ventricular dysfunction among OB patients with a history of heart disease can be detected with this serum assay. A prospective cohort design consisting of two groups of pregnant patients; one with a history of cardiac disease and one without, will be followed over the course of the pregnancies and cardiac function will be measured using echocardiography and serum BNP. It is hoped that the blood test for BNP will be a reliable way to help evaluate OB patients with suspected abnormal heart function.