Early pregnancy changes in hemodynamics and volume homeostasis are consecutive adjustments triggered by a primary fall in systemic vascular tone

doi:10.1016/0002-9378(93)90405-8

American Journal of Obstetrics and Gynecology

Volume 169, Issue 6, December 1993, Pages 1382-1392

https://doi.org/10.1016/0002-9378(93)90405-8 Get rights and content

OBJECTIVE: The purpose of this study was to test the hypothesis that early pregnancy changes in volume homeostasis develop as a consequence of preceding changes in maternal hemodynamics.

STUDY DESIGN: Maternal cardiovascular function of 10 pregnant women was followed up by Doppler echocardiography. Vascular filling state and volume homeostasis were evaluated by echocardiographic index values, glomerular filtration rate, serum osmolality, and volume-regulating hormones. Studies were performed weekly in early pregnancy, in the second and third trimesters, and post partum. Changes relative to the fifth week and the consistency of changes between weeks 5 and 8 were evaluated by nonparametric statistics.

RESULTS: In early pregnancy cardiac output increased and afterload decreased. Concomitant increases in ultrasonic preload index values and glomerular filtration rate were accompanied by decreases in serum renin, Na+, and osmolality.

CONCLUSION: These data support the concept that maternal hemodynamic adaptation to pregnancy is most likely triggered by a primary fall in systemic vascular tone. The resulting rapid fall in preload and afterload leads to a compensatory increase in heart rate and activation of the volume-restoring mechanisms. Subsequently cardiac output increases because of a rise in stroke volume, which develops because the vascular filling state normalizes, whereas the reduced afterload reduction is maintained.

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^*: Presented in part at the Thirty-ninth Annual Meeting of the Society for Gynecologic Investigation, San Antonio, Texas, March 18–21, 1992.

^a: From the Department of Obstetrics and Gynecology

^b: From the Department of Cardiology

^c: From the Department of Clinical Chemistry, Academic Hospital Maastricht

View full text

Early pregnancy changes in hemodynamics and volume homeostasis are consecutive adjustments triggered by a primary fall in systemic vascular tone*

Am J Obstet Gynecol

Am J Obstet Gynecol

J Am Coll Cardiol

J Am Coll Cardiol

Am J Obstet Gynecol

[Letter] Am J Obstet Gynecol

Gastroenterology

Increase in plasma volume during normal pregnancy

J Obstet Gynaecol Br Commonw

Plasma volume in normal first pregnancy

J Obstet Gynaecol Br Commonw

Circulatory adaptation to pregnancy — serial studies of haemodynam-ics, blood volume, renine and aldosterone in the baboon (Papio hamadryas)

J Hypertens

Serial study of factors influencing changes in cardiac output during human pregnancy

Am J Physiol

Noninvasive Doppler determination of cardiac output in man: clinical validation

Circulation

Combined Doppler and echocardiographic measurement of cardiac output: theory and application in pregnancy

Br J Obstet Gynaecol

Plasma osmolality and urinary concentration and dilution during and after pregnancy: evidence that lateral recumbency inhibits maximal urinary concentrating ability

Br J Obstet Gynaecol

Peripheral arterial vasodilatation hypothesis of sodium and water retention in pregnancy: implications for pathogenesis of preeclampsia-eclampsia

Obstet Gynecol

Recommendations regarding quantifications in M-mode echocardiographic measurements

Circulation

Echocardiographic determination of the left ventricular mass in man. Anatomic validation of the method

Circulation

Evaluation of left ventricular function by echocardiography

Circulation