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Maternal dehydration-rehydration: fetal plasma and urinary responses
M G Ross1, D J Sherman, M G Ervin
1Department of Obstetrics, Harbor-UCLA Medical Center, Torrance 90509.
The American Journal of Physiology
|November 1, 1988
Summary
Maternal dehydration during pregnancy increases fetal osmolality and arginine vasopressin (AVP) levels. Even after rehydration, fetal responses like AVP secretion and altered urine production persist, indicating prolonged effects.
Area of Science:
- Physiology
- Perinatal Medicine
- Reproductive Biology
Background:
- Pregnant women can experience dehydration from exercise, heat, or hyperemesis, leading to increased plasma osmolality.
- Fetal osmolality is linked to maternal osmolality, but the fetal response to maternal dehydration and rehydration remains understudied.
Purpose of the Study:
- To investigate the impact of maternal dehydration and subsequent rehydration on fetal physiological parameters.
Main Methods:
- Five pregnant ewes were dehydrated for 36 hours, followed by a 4-hour rehydration period using intravenous saline.
- Measurements included maternal and fetal plasma osmolality, fetal arginine vasopressin (AVP) levels, hematocrit, glomerular filtration rate, and urine production.
Main Results:
- Maternal dehydration caused significant increases in fetal plasma osmolality, AVP levels, hematocrit, and urine osmolality.
- Following maternal rehydration, fetal glomerular filtration rate and urine volume increased, but fetal hematocrit, AVP levels, and urine osmolality did not return to baseline.
Conclusions:
- Maternal dehydration induces fetal hyperosmolality, hemoconcentration, AVP release, and altered urine production.
- Fetal endocrine and fluid balance responses to maternal dehydration are prolonged, persisting even after maternal plasma osmolality normalizes.