Nahum Gerard G, Stanislaw Harold
Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Reprod Med. 2004 Apr;49(4):297-305.
To investigate the relationship between maternal hemoglobin concentration, altitude and birth weight.
Birth weights in 235 term pregnancies were investigated for their dependence on maternal hemoglobin concentration after other maternal and pregnancy-specific influences on fetal weight were taken into account. The additional predictive value of hemoglobin concentration on birth weight was assessed using multiple regression. Using published data, the relationship of hemoglobin concentration to altitude was determined, as was the effect of increasing altitude on birth weight. The quantitative effect of hemoglobin concentration on birth weight was correlated with the effect of altitude on hemoglobin concentration to assess whether this could account for the known decrease in birth weight with increasing altitude.
Birth weights ranged from 2,220 to 4,850 g (mean, 3,505+/-443), and hemoglobin concentrations ranged from 9.3 to 13.5 g/dL (mean, 11.6+/-0.8). Apart from other known predictive variables, the variation in maternal hemoglobin concentrations at constant altitude independently explained 2.6% of the variance in birth weight (r=-.18, P=.003). Term birth weight was reduced by 89 g for each 1.0 g/dL increase in hemoglobin concentration (P<.01). For every 1,000-m increase in altitude, hemoglobin concentration increased by 1.52 g/dL and birth weight decreased by 117 g.
Birth weight correlates negatively with maternal hemoglobin concentration. This is consistent with the well-known effect of high-altitude exposure during pregnancy, which increases both hematocrit and blood viscosity and lowers birth weight. The quantitative effect on birth weight of increasing maternal hemoglobin concentration at constant altitude is within 13% of the change in birth weight that can be attributed to the change in hemoglobin concentration associated with increases in altitude.
探讨孕妇血红蛋白浓度、海拔高度与出生体重之间的关系。
在考虑了其他对胎儿体重有影响的孕妇及孕期特定因素后，对235例足月妊娠的出生体重与孕妇血红蛋白浓度的相关性进行研究。采用多元回归评估血红蛋白浓度对出生体重的额外预测价值。利用已发表的数据，确定血红蛋白浓度与海拔高度的关系，以及海拔升高对出生体重的影响。将海拔高度不变时孕妇血红蛋白浓度对出生体重的定量影响与海拔高度对血红蛋白浓度的影响进行关联分析，以评估这是否能解释随着海拔升高出生体重下降这一已知现象。
出生体重范围为2220至4850克（平均为3505±443克），血红蛋白浓度范围为9.3至13.5克/分升（平均为11.6±0.8克/分升）。除其他已知的预测变量外，在海拔高度不变的情况下，孕妇血红蛋白浓度的变化独立解释了出生体重变异的2.6%（r = -0.18，P = 0.003）。血红蛋白浓度每升高1.0克/分升，足月出生体重降低89克（P < 0.01）。海拔每升高1000米，血红蛋白浓度升高1.52克/分升，出生体重降低117克。
出生体重与孕妇血红蛋白浓度呈负相关。这与孕期暴露于高海拔环境的已知影响一致，即高海拔会增加血细胞比容和血液粘度，并降低出生体重。在海拔高度不变的情况下，孕妇血红蛋白浓度升高对出生体重的定量影响在可归因于海拔升高导致的血红蛋白浓度变化所引起的出生体重变化的13%以内。
