Obstet Gynecol Surv. 2005 Feb;60(2):78-80. Related Articles, Links
Pregnancy at High Altitude: A Hyperviscosity State.
Kametas NA, Krampl E, McAuliffe F, Rampling MW, Nicolaides KH.
Harris Birthright Research Center for Fetal Medicine, King's College
Hospital, London, and CIBS, Imperial College School of Medicine,
London, U.K.
In nonpregnant subjects, the state of hypobaric hypoxia existing at
high altitude is associated with increased erythropoiesis and reduced
total body water, leading inevitably to hyperviscosity. Hyperviscosity
in women at altitude has been linked with intrauterine growth
restriction and preeclampsia. This cross-sectional study enrolled 94
women having singleton pregnancies who lived 4370 meters above sea
level. They were evaluated when coming for routine antenatal care at 10
to 38 weeks gestation, along with 75 women living at sea level.
Nonpregnant control women included 24 living at altitude and 17 at sea
level.In nonpregnant control women, blood viscosity was higher at high
altitude. In pregnant women, whether at sea level or high altitude,
blood viscosity declined as gestation advanced but was significantly
higher at altitude than at sea level. Hematocrit also decreased during
gestation; levels were higher at altitude. At high altitude, hematocrit
levels were higher in pregnant than in nonpregnant control women.
Plasma viscosity decreased during gestation in pregnant women at sea
level but did not change in the high-altitude group. Total protein
levels decreased as gestation proceeded in both groups of pregnant
women but were higher in the high-altitude group. At altitude, total
protein levels were lower in pregnant women. Fibrinogen levels were
higher at altitude than at sea level. In pregnant women at sea level,
concentrations increased with gestation. At altitude, fibrinogen levels
were similar in pregnant and nonpregnant women. Albumin concentrations
decreased with gestation both at sea level and at high altitude. Levels
were lower at high altitude than at sea level in pregnant women. At
altitude, albumin levels were lower in pregnant women than in the
nonpregnant control women.This study demonstrates that, in pregnant
women living at high altitude, blood viscosity is increased as a result
of increases in hematocrit and plasma viscosity. The result may be
increased resistance to blood flow in the placental bed, which has a
sensitive low-shear circulation. Whether hyperviscosity affects fetal
and maternal adaptation during pregnancy at high altitude remains to be
determined.
PMID: 15671881 [PubMed - as supplied by publisher]
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