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Lowland origin women raised at high altitude are not protected against lower uteroplacental O 2 delivery during pregnancy or reduced birth weight
Author(s) -
Julian Colleen G.,
Hageman Jennifer L.,
Wilson Megan J.,
Vargas Enrique,
Moore Lorna G.
Publication year - 2011
Publication title -
american journal of human biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.559
H-Index - 81
eISSN - 1520-6300
pISSN - 1042-0533
DOI - 10.1002/ajhb.21167
Subject(s) - pregnancy , effects of high altitude on humans , altitude (triangle) , birth weight , low birth weight , fetus , medicine , demography , obstetrics , biology , genetics , geometry , mathematics , sociology , anatomy
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. Am. J. Hum. Biol. 2011. © 2011 Wiley‐Liss, Inc.