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Am J Hum Biol. 2011 Jul-Aug;23(4):509-16. doi: 10.1002/ajhb.21167. Epub 2011 Apr 27.

Lowland origin women raised at high altitude are not protected against lower uteroplacental O2 delivery during pregnancy or reduced birth weight.

Author information

1
Department of Emergency Medicine, Altitude Research Center, University of Colorado Denver, Aurora, USA. colleen.julian@ucdenver.edu

Abstract

OBJECTIVE:

Maternal physiologic responses to pregnancy promoting fetal oxygen and nutrient delivery are important determinants of reproductive success. Incomplete physiologic compensation for reduced oxygen availability at high altitude (≥2,500 m) compromises fetal growth. Populations of highland (e.g., Andeans, Tibetans) compared with lowland origin groups (e.g., Europeans, Han Chinese) are protected from this altitude-associated decrease in birth weight; here we sought to determine whether maternal development at high altitude-rather than highland ancestry-contributed to the protection of birth weight and uterine artery (UA) blood flow during pregnancy.

METHODS:

In women of lowland ancestry who were either raised at high altitude in La Paz, Bolivia (3,600-4,100 m) ("lifelong," n = 18) or who had migrated there as adults ("newcomers," n = 40) we compared maternal O(2) transport during pregnancy and their infant's birth weight.

RESULTS:

Pregnancy raised maternal ventilation and arterial O(2) saturation equally, with the result that arterial O(2) content was similarly maintained at nonpregnant levels despite a fall in hemoglobin. UA blood flow and uteroplacental O(2) delivery were lower in lifelong than newcomer residents (main effect). Birth weight was similar in lifelong residents versus newcomers (2,948 ± 93 vs. 3,090 ± 70 gm), with both having values below those of a subset of eight high-altitude residents who descended to deliver at low altitude (3,418 ± 133 gm, P < 0.05).

CONCLUSION:

Lifelong compared with newcomer high-altitude residents have lower uteroplacental O(2) delivery and similar infant birth weights, suggesting that developmental factors are likely not responsible for the protective effect of highland ancestry.

PMID:
21538651
DOI:
10.1002/ajhb.21167
[Indexed for MEDLINE]

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