Neural control of blood pressure during pregnancy in humans

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REVIEW ARTICLE

Neural control of blood pressure during pregnancy in humans Sarah L. Hissen1,2 · Qi Fu1,2  Received: 25 March 2020 / Accepted: 10 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Purpose  Previous microneurographic studies found that muscle sympathetic nerve activity (MSNA) increased in normotensive pregnant women and was even greater in women with gestational hypertension and preeclampsia during the third trimester. It is possible that sympathetic activation during the latter months of normal pregnancy helps return arterial pressure to non-pregnant levels. However, when the increase in sympathetic activity is excessive, hypertension ensues. The key question that must be addressed is whether sympathetic activation develops early during pregnancy and remains high throughout gestation, or whether this sympathetic overactivity only occurs at term, providing the substrate for preeclampsia and other pregnancy-associated cardiovascular complications. Methods  This was a literature review of autonomic neural control during pregnancy. Results  Recent work from our laboratory and other laboratories showed that in healthy women resting MSNA increased in early pregnancy, increased further in late pregnancy, and returned to the pre-pregnancy levels shortly after delivery. We found that women who exhibited excessive sympathetic activation during the first trimester, before any clinical signs and symptoms appeared, developed gestational hypertension at term. We also found that the level of corin, an atrial natriuretic peptide-converting enzyme, was increased in the maternal circulation, especially during late pregnancy, as a homeostatic response to elevated sympathetic activity. Conclusion  These findings provide important insight into the neural mechanisms underlying hypertensive disorders during pregnancy. With this knowledge, early prevention or treatment targeted to the appropriate pathophysiology may be initiated, which may reduce maternal and fetal death or morbidity, as well as cardiovascular risks in women later in life. Keywords  Muscle sympathetic nerve activity · Blood pressure · Hemodynamics · Pregnancy

Introduction Pregnancy is associated with significant changes in maternal hemodynamics that begin as early as 4 weeks of gestation, prior to the presence of the fetal–placental unit, and plateaus at approximately 20 weeks or during the second trimester. During the entire course of pregnancy, cardiac output, blood volume, heart rate, and stroke volume increase, and total peripheral resistance decreases [1, 2]. Activation of

* Qi Fu [email protected] 1



Women’s Heart Health Laboratory, Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, 7232 Greenville Avenue, Suite 435, Dallas, TX 75231, USA



Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA

2

the renin–angiotensin–aldosterone system increases sodium and water reabsorption from the kidneys, increasing blood volume [2]. Atria