BACKGROUND:

The renin-angiotensin system is involved in the physiology of pregnancy in two ways. Circulating angiotensin II affects blood pressure, renal hemodynamics, and uteroplacental blood flow. Abnormalities in angiotensin II production rates in hypertensive pregnancy contribute to the hemodynamic changes seen in the disease. Additionally, there is a form of the renin-angiotensin system in kidney, ovary, and placenta whose function is regulated by prorenin. Prorenin, activated by a specific receptor, is involved in the regulation of steroid hormone biosynthesis and renal and uteroplacental blood flow.

The study was conducted in response to a Request for Applications on Research on Hypertension in Pregnancy jointly released in 1986 by the National Heart, Lung, and Blood Institute and the National Institute of Child Health and Human Development.

DESIGN NARRATIVE:

The study was longitudinal in design. Measurements were made of glomerular filtration rate, renal plasma flow or uterine blood flow. To define first trimester changes, studies were conducted on in vitro fertilization and ovarian failure patients who had a broad spectrum of plasma prorenins. Since interrelated changes in renin and prostaglandins may participate in the pathogenesis of hypertensive pregnancy, RAAS, prostaglandins, and uteroplacental flow velocity profiles were monitored during a placebo-controlled trial of low-dose aspirin in chronic hypertensives.