Atrial Natriuretic Peptide (ANP) in Normal Pregnancy; A Longitudinal Study

Abstract

Plasma levels of atrial natriuretic peptide (ANP) were studied in 23 nulliparous women longitudinally during normal pregnancy in relation to various cardiovascular and urinary parameters. Concentrations of ANP were significantly increased at the 20th gestational week as compared with values 6 weeks post partum. During the second half of pregnancy ANP levels showed a significant decrease towards levels not much different from those 6 weeks after delivery. Gestational ANP levels were significantly inversely correlated with weight, systemic vascular resistance and systolic blood pressure. ANP was neither correlated with atrial or ventricular dimensions, natriuresis nor diuresis. The results might suggest that in the course of pregnancy the regulation of ANP secretion takes place around a new volume ‘set-point’. The finding of gestational plasma levels of ANP within the non-pregnant range does, however, not exclude some enhanced cardiac production of ANP, in view of the increased volume of distribution and probably an enhanced rate of clearance.