The four interrelated approaches in the study should lead to a better understanding of the role of angiotensinogen in pregnancy and of the pathophysiology of preeclampsia. Unlike any previous finding in preeclamptic patients, the genetic alteration in angiotensinogen described is an intrinsic defect which, although it may be modified by other factors, cannot be 'secondary' to other pathophysiologic variables. This molecular hypothesis demands a reinterpretation of many prior findings in preeclampsia, fetal growth retardation, and premature labor based on angiotensinogen genotypes. The DNA and plasma collected for this study will be invaluable resources for future molecular investigations of abnormal pregnancies.