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
Hospital Materno-Infantil, Universidad de San Andreas Mayor, La Paz, Bolivia.
J Physiol. 2009 Feb 1;587(3):693-708. doi: 10.1113/jphysiol.2008.163634. Epub 2008 Dec 15.
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.
高海拔地区（>2700米）胎儿生长减缓。我们推测胎儿氧输送的差异可能是导致海拔效应以及高海拔地区多代原住民胎儿生长相对得以维持的原因。研究对象为168名欧洲或安第斯血统的女性，她们分别居住在海拔3600米或400米的地区。血统经基因确认。使用超声和多普勒测量脐静脉血流量。采集脐血样本以计算胎儿的氧输送量和消耗量。无论海拔如何，安第斯胎儿的血流量和氧输送量均高于欧洲胎儿，且出生体重更重（重208克，P<0.0001）。在海拔3600米处胎儿血流量减少（P<0.0001）；两个血统组的减少幅度相似。欧洲人因海拔导致的出生体重下降幅度（-417克）大于安第斯人（-228克，P<0.005）。在任何给定的血流量或氧输送水平下，海拔3600米处欧洲人的出生体重比安第斯人低>200克。在海拔3600米处，胎儿血红蛋白浓度升高、降低，胎儿氧解离曲线左移。氧输送量较低的胎儿提取的氧量更多（r2 = 0.35，P<0.0001）。这些适应性变化使得所有四组胎儿的氧输送量和消耗量相似。脐静脉氧输送量增加与每千克体重胎儿氧消耗量增加相关（r2 = 0.50，P<0.0001）。在海拔3600米处，血流量（r2 = 0.16，P<0.001）和氧输送量（r2 = 0.17，P<0.001）与出生体重相关，但在海拔400米处不相关（分别为r2 = 0.04和0.03）。我们得出结论，高海拔地区最显著的差异是胎儿血流量减少，但胎儿血液学适应性变化以及胎儿增加氧提取的能力表明，胎儿氧输送不足不太可能与胎儿生长的海拔和血统相关差异存在因果关系。
