Augmented uterine artery blood flow and oxygen delivery protect andeans from altitude-associated reductions in fetal growth
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2009-02-20Autor
Julian, Colleen Glyde
Wilson, Megan J
López, Miriam
Yamashiro, Henry
Téllez, Wilma
Rodríguez, Armando
Bigham, Abigail W
Shriver, Mark D
Rodríguez, Carmelo
Vargas, Enrique
Moore, Lorna G
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Abstract.
The effect of high altitude on reducing birth weight is markedly less in
populations of high- (e.g., Andeans) relative to low-altitude origin
(e.g., Europeans). Uterine artery (UA) blood flow is greater during
pregnancy in Andeans than Europeans at high altitude; however, it is
not clear whether such blood flow differences play a causal role in
ancestry-associated variations in fetal growth. We tested the hypothesis that greater UA blood flow contributes to the protection of fetal
growth afforded by Andean ancestry by comparing UA blood flow
and fetal growth throughout pregnancy in 137 Andean or European
residents of low (400 m; European n 28, Andean n 23) or high
(3,100–4,100 m; European n 51, Andean n 35) altitude in
Bolivia. Blood flow and fetal biometry were assessed by Doppler
ultrasound, and maternal ancestry was confirmed, using a panel of 100
ancestry-informative genetic markers (AIMs). At low altitude, there
were no ancestry-related differences in the pregnancy-associated rise
in UA blood flow, fetal biometry, or birth weight. At high altitude,
Andean infants weighed 253 g more than European infants after
controlling for gestational age and other known influences. UA blood
flow and O2 delivery were twofold greater at 20 wk in Andean than
European women at high altitude, and were paralleled by greater fetal
size. Moreover, variation in the proportion of Indigenous American
ancestry among individual women was positively associated with UA
diameter, blood flow, O2 delivery, and fetal head circumference. We
concluded that greater UA blood flow protects against hypoxiaassociated reductions in fetal growth, consistent with the hypothesis that genetic factors enabled Andeans to achieve a greater pregnancyassociated rise in UA blood flow and O2 delivery than European women at high altitude.