title: Lowland origin women raised at high altitude are not protected against lower uteroplacental O2 delivery during pregnancy or reduced birth weight.
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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Emergency Medicine, Altitude Research Center, University of Colorado Denver, Aurora, USA. colleen.julian@ucdenver.edu
authors.forename: Colleen G
authors.initials: CG
authors.lastname: Julian
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Hageman
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Wilson
authors.forename: Enrique
authors.initials: E
authors.lastname: Vargas
authors.forename: Lorna G
authors.initials: LG
authors.lastname: Moore
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000367:Age Factors; D000531:Altitude; D000532:Altitude Sickness; D001034:Apgar Score; D001838:Bolivia; D002648:Child; D016001:Confidence Intervals; D036861:Delivery, Obstetric; D005260:Female; D005843:Geography; D006439:Hemodynamics; D006454:Hemoglobins; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008603:Mental Health; D010100:Oxygen / Q000097:blood* / Q000378:metabolism; D010101:Oxygen Consumption; D011247:Pregnancy; D011256:Pregnancy Outcome; D011795:Surveys and Questionnaires; D013997:Time Factors; D055988:Uterine Artery; D016387:Women's Health
chemical_list: D006454:Hemoglobins; D010100:Oxygen