Preeclampsia and maladaptation to pregnancy: A role for atrial natriureticpeptide?

Background. The majority of women with a history of preeclampsia have eithe r an underlying thrombophilic disorder or a vascular disorder. In this stud y, we tested the hypothesis that only the latter condition predisposes for abnormal hemodynamic adaptation to pregnancy. Methods. Thirty-seven formerly preeclamptic subjects were subdivided into a hypertensive (HYPERT, N = 10) a normotensive thrombophilic (THROMB, N = 13 ) and a normotensive nonthrombophilic subgroup (NONTHROMB, N = 14). In thes e women and in 10 normal parous controls, the following variables were meas ured at least five-months postpartum at day 5 (+/-2) of the menstrual cycle and again at five- and seven-weeks amenorrhea in the next pregnancy: mean arterial pressure, heart rate, cardiac output, central cardiovascular dimen sions. plasma volume, glomerular filtration rate, effective renal plasma fl ow, 17-beta estradiol, progesterone, the hormones of the renin-angiotensin- aldosterone (RAAS) axis, catecholamines and alpha -atrial natriuretic pepti de. Results. The early pregnancy rise in cardiac output, renal variables. RAAS activity, and plasma volume was comparable in all groups. However, the HYPE RT and NONTHROMB subgroups differed from controls by a lower plasma volume in the prepregnant state. In addition, only the women in these two subgroup s responded to pregnancy by a rise in circulating a.-atrial natriuretic pep tide. In addition, at seven weeks, in the subjects belonging to the HYPERT and NONTHROMB subgroups, plasma volume was the lowest and correlated invers ely with the concomitant circulating level of alpha -atrial natriuretic pep tide. Conclusion. The hemodynamic adaptation to pregnancy in the HYPE RT and NONT HROMB subgroups differs from that in THROMB and controls by an early pregna ncy rise in a-atrial natriuretic peptide. As a consequence, the early pregn ancy plasma volume expansion in the NONTHROMB and HYPERT subgroups is less than in normal parous controls.