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Whole blood viscosity during normal pregnancy
A Huisman1, J G Aarnoudse, J H Heuvelmans
1Department of Obstetrics, University of Groningen, The Netherlands.
British Journal of Obstetrics and Gynaecology
|December 1, 1987
Summary
During normal pregnancy, whole blood viscosity initially decreases then slightly increases, influenced mainly by hematocrit and plasma viscosity changes. Red cell aggregation did not affect viscosity in this study.
Area of Science:
- Obstetrics and Gynecology
- Physiology
- Biomedical Engineering
Background:
- Pregnancy involves significant physiological adaptations.
- Understanding hemorheological changes during pregnancy is crucial for maternal and fetal health.
Purpose of the Study:
- To investigate serial changes in whole blood viscosity and its determinants during normal pregnancy.
- To assess the influence of hematocrit, plasma viscosity, and red cell aggregation on blood viscosity throughout gestation.
Main Methods:
- Serial measurements of whole blood viscosity at various shear rates using a rotational viscometer.
- Determination of plasma viscosity and red cell aggregation (syllectometry).
- Study included 24 healthy pregnant women.
Main Results:
- Whole blood viscosity decreased until 29 weeks gestation, followed by a modest increase up to 37 weeks.
- Changes in viscosity were primarily driven by alterations in hematocrit and plasma viscosity.
- Hematocrit significantly impacted low shear rate viscosity, while plasma viscosity influenced high shear rate viscosity.
- Increased red cell aggregation showed no measurable effect on low shear rate viscosity in vitro.
Conclusions:
- Pregnancy-induced hemorheological changes are complex, with viscosity dynamics influenced by hematocrit and plasma viscosity.
- The relative importance of hematocrit and plasma viscosity varies with shear rate.
- Red cell aggregation's role in low shear viscosity may be limited under these specific in vitro conditions.