Pregnancy at high altitude: a hyperviscosity state.
BACKGROUND
Pregnancy at high altitude has been associated with intrauterine growth restriction and preeclampsia. These conditions, at sea level, have been linked to increased hematocrit and blood viscosity. The aim of this study was to investigate the effect of high altitude on maternal hemorheology.


METHODS
This was a cross-sectional study. We examined 94 pregnant women at 10-38 weeks of gestation resident at high altitude (4370 m above sea level) and 75 at sea level, and 24 and 17 nonpregnant women at each altitude, respectively. Blood and plasma viscosity, hematocrit, plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting.


RESULTS
Pregnancy at high altitude, compared to sea level, is characterized by higher hematocrit, blood viscosity (at high shear rate), plasma viscosity, total protein and fibrinogen concentrations (25%, 38%, 7%, 13.3% and 25%, respectively) and 6% lower albumin concentration. Nonpregnant women at high altitude, compared to sea level, had higher hematocrits, blood viscosity, plasma viscosity, total protein and fibrinogen concentrations (25%, 55%, 18%, 26% and 98%, respectively) and 13% lower albumin concentration.


CONCLUSIONS
Pregnancy at high altitude compared to sea level is characterized by increased blood viscosity as a result of increased hematocrit and plasma viscosity.
Kametas
Nikos A
NA
Harris Birthright Research Center for Fetal Medicine, King's College Hospital, London, UK. n.kametas@btinternet.com
Krampl
Elisabeth
E
McAuliffe
Fionnuala
F
Rampling
Michael W
MW
Nicolaides
Kypros H
KH
D000328:Adult; D000531:Altitude; D001798:Blood Proteins / Q000032:analysis; D001809:Blood Viscosity / Q000502:physiology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006400:Hematocrit; D018056:Hemorheology; D006801:Humans; D011247:Pregnancy / Q000097:blood*; D012709:Serum Albumin / Q000032:analysis
D001798:Blood Proteins; D012709:Serum Albumin; D005340:Fibrinogen