Preliminary clinical experience indicates that serum BNP levels obtained by a commercially available rapid assay method may be related to the degree of ventricular dysfunction among obstetrical patients with acute dyspnea associated with preeclampsia, tocolysis therapy, or an underlying history of cardiopulmonary disease (6). The purpose of this protocol is to determine prospectively if the measurement of serum BNP levels will correlate with cardiac function changes noted on echocardiography and clinically among pregnant women with a history of cardiac disease. This group is to be compared to a group of pregnant women with no history of cardiac disease.