title: Higher estrogen levels during pregnancy in Andean than European residents of high altitude suggest differences in aromatase activity.
abstract: BACKGROUND
  Uteroplacental hypoxia has been reported to lower estrogen levels in preeclampsia as the result of reduced aromatase activity.
  
  
  OBJECTIVE
  We asked whether the chronic hypoxia of residence at high altitude in the absence of preeclampsia lowered estrogen, whether such effects differed in Andean vs European high-altitude residents, and whether such effects were related to uterine artery diameter or blood flow.
  
  
  METHODS
  Studies at weeks 20 and 36 of pregnancy were conducted in 108 healthy Bolivian low- (400 m, n = 53) or high-altitude (3600 m, n = 55) residents of European (n = 28 low and 26 high altitude) or Andean (n = 25 low and 29 high altitude) ancestry. All groups were similar in age, nonpregnant body mass index, and pregnancy weight gain.
  
  
  RESULTS
  High-altitude residence increased circulating progesterone, cortisol, estrone, 17β-estradiol, and estriol levels (all P < .01). High-altitude Andeans vs Europeans at week 36 had higher progesterone, estrone, 17β-estradiol, and estriol levels as well as product to substrate ratios for the reactions catalyzed by aromatase, whereas week 36 cortisol levels were greater in the European than Andean women (all P < .05). Lower cortisol, higher estriol (both P < .01), and trends for higher progesterone and 17β-estradiol levels were associated with greater uterine artery diameters and blood flow at high altitude.
  
  
  CONCLUSIONS
  Chronic hypoxia does not lower but rather raises estrogen levels in multigenerational Andeans vs shorter-term Europeans, possibly as the result of greater aromatase activity. Because hypoxia alone does not lower estrogen, other attributes of the disease may be responsible for the lower estrogen levels seen previously in preeclamptic women.
authors.affiliation: Department of Obstetrics and Gynecology (S.M.C.), Wake Forest University, Winston-Salem, North Carolina 27157; Division of Biomedical Informatics and Personalized Medicine (C.G.J.), Departments of Medicine and Obstetrics and Gynecology (L.G.M.), University of Colorado Denver, Aurora, Colorado 80045; and Instituto de Biología de Altura (E.V.), La Paz, Bolivia.
authors.forename: Shelton M
authors.initials: SM
authors.lastname: Charles
authors.forename: Colleen G
authors.initials: CG
authors.lastname: Julian
authors.forename: Enrique
authors.initials: E
authors.lastname: Vargas
authors.forename: Lorna G
authors.initials: LG
authors.lastname: Moore
mesh_terms: D000328:Adult; D000531:Altitude; D001141:Aromatase / Q000378:metabolism*; D001838:Bolivia / Q000453:epidemiology; D004967:Estrogens / Q000097:blood*; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D021041:Placental Circulation; D011247:Pregnancy / Q000097:blood*; D012039:Regional Blood Flow; D013020:South America / Q000453:epidemiology; D014463:Ultrasonography; D055988:Uterine Artery / Q000000981:diagnostic imaging; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D004967:Estrogens; D012739:Gonadal Steroid Hormones; D001141:Aromatase