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Where the O 2 goes to: preservation of human fetal oxygen delivery and consumption at high altitude
Author(s) -
Postigo Lucrecia,
Heredia Gladys,
Illsley Nicholas P.,
Torricos Tatiana,
Dolan Caitlin,
Echalar Lourdes,
Tellez Wilma,
Maldonado Ivan,
Brimacombe Michael,
Balanza Elfride,
Vargas Enrique,
Zamudio Stacy
Publication year - 2009
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2008.163634
Subject(s) - fetus , effects of high altitude on humans , umbilical vein , altitude (triangle) , umbilical cord , birth weight , blood flow , zoology , medicine , fetal weight , fetal growth , pregnancy , andrology , endocrinology , physiology , biology , anatomy , biochemistry , genetics , geometry , mathematics , in vitro
Fetal growth is decreased at high altitude (> 2700 m). We hypothesized that variation in fetal O 2 delivery might account for both the altitude effect and the relative preservation of fetal growth in multigenerational natives to high altitude. Participants were 168 women of European or Andean ancestry living at 3600 m or 400 m. Ancestry was genetically confirmed. Umbilical vein blood flow was measured using ultrasound and Doppler. Cord blood samples permitted calculation of fetal O 2 delivery and consumption. Andean fetuses had greater blood flow and oxygen delivery than Europeans and weighed more at birth, regardless of altitude (+208 g, P < 0.0001). Fetal blood flow was decreased at 3600 m ( P < 0.0001); the decrement was similar in both ancestry groups. Altitude‐associated decrease in birth weight was greater in Europeans (−417 g) than Andeans (−228 g, P < 0.005). Birth weight at 3600 m was > 200 g lower for Europeans at any given level of blood flow or O 2 delivery. Fetal haemoglobin concentration was increased, decreased, and the fetal / curve was left‐shifted at 3600 m. Fetuses receiving less O 2 extracted more ( r 2 = 0.35, P < 0.0001). These adaptations resulted in similar fetal O 2 delivery and consumption across all four groups. Increased umbilical venous O 2 delivery correlated with increased fetal O 2 consumption per kg weight ( r 2 = 0.50, P < 0.0001). Blood flow ( r 2 = 0.16, P < 0.001) and O 2 delivery ( r 2 = 0.17, P < 0.001) correlated with birth weight at 3600 m, but not at 400 m ( r 2 = 0.04, and 0.03, respectively). We concluded that the most pronounced difference at high altitude is reduced fetal blood flow, but fetal haematological adaptation and fetal capacity to increase O 2 extraction indicates that deficit in fetal oxygen delivery is unlikely to be causally associated with the altitude‐ and ancestry‐related differences in fetal growth.