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The 4-vessel Sampling Approach to Integrative Studies of Human Placental Physiology In Vivo
Published on: August 2, 2017
Temporal relationships between hormonal and hemodynamic changes in early human pregnancy
A B Chapman1, W T Abraham, S Zamudio
1Department of Medicine, University of Colorado Health Sciences Center, St. Louis, Missouri, USA. arlenevchapman@emory.org
Kidney International
|December 16, 1998
Summary
Early pregnancy involves significant hemodynamic shifts, including decreased blood pressure and increased cardiac output, occurring before the placenta fully develops. These changes are linked to early vasodilation and hormonal adjustments.
Area of Science:
- Physiology
- Reproductive Medicine
- Cardiovascular Science
Background:
- Human pregnancy typically features reduced mean arterial pressure, elevated cardiac output, and expanded plasma volume.
- Increased renal plasma flow and glomerular filtration rate are also characteristic of pregnancy hemodynamics.
- The precise timing and causative factors of early pregnancy hemodynamic changes remain incompletely understood.
Purpose of the Study:
- To investigate the temporal sequence of systemic and renal hemodynamic alterations in early human pregnancy.
- To determine if these hemodynamic changes precede the establishment of the fetal-placental unit.
Main Methods:
- Studied thirteen women at multiple time points: pre-conception and at gestational weeks 6, 8, 10, 12, 24, and 36.
- Measured mean arterial pressure, cardiac output, and inulin and para-aminohippuric acid (PAH) clearance.
- Assessed plasma renin activity, aldosterone, norepinephrine, atrial natriuretic peptide (ANP), and cyclic guanosine monophosphate (cGMP) levels.
Main Results:
- Mean arterial pressure significantly decreased by gestational week 6, accompanied by increased cardiac output, reduced systemic vascular resistance, and expanded plasma volume.
- Renal plasma flow and glomerular filtration rate increased by week 6.
- Renin-angiotensin-aldosterone system components (renin activity, aldosterone) rose by week 6; ANP increased later at week 12.
Conclusions:
- Early pregnancy is marked by peripheral and renal vasodilation, preceding full placentation.
- The renin-angiotensin-aldosterone system is activated early in pregnancy.
- Plasma volume expansion occurs early, with subsequent increases in ANP suggesting a response to volume changes.
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