title: Maternal serum insulin-like growth factor binding protein-1 in pregnancy at high altitude.
abstract: OBJECTIVE
  To investigate the effect of environmental hypoxia at 4300-m altitude on the maternal serum concentration of insulin-like growth factor binding protein-1 (IGFBP-1).
  
  
  METHODS
  We conducted a cross-sectional study of 108 pregnant women in Peru, 62 from high altitude (4300 m, 14100 ft) and 46 from sea level at 14-42 weeks' gestation. For comparison, 20 healthy nonpregnant women (ten from high altitude and ten from sea level) were also examined. Total and nonphosphorylated IGFBP-1 were measured in maternal serum.
  
  
  RESULTS
  Both total and nonphosphorylated IGFBP-1 were higher at high altitude than at sea level in the pregnant groups (ratio = 1.28, P =.008, and ratio = 1.45, P =.003, respectively), and there was significant interaction between high altitude and sea level (P =.037 and P =.043, respectively). The threshold model showed that the difference became significant from 25 weeks' gestation onwards.
  
  
  CONCLUSIONS
  Before 25 weeks of pregnancy, there was no significant difference in IGFBP-1 between women living at high or low altitude, suggesting that the increased IGFBP-1 at high altitude is unlikely to be related to inadequate trophoblast invasion resulting in placental hypoxia. In the second half of pregnancy, the maternal and fetal demands increase dramatically, and low atmospheric oxygen with resulting maternal systemic hypoxemic hypoxia may cause placental hypoxia. This stimulates increased production of IGFBP-1, which in turn restricts the insulin-like growth factor-mediated fetal growth as an adaptive mechanism to prevent worsening of the fetoplacental hypoxia.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, United Kingdom
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Krampl
authors.forename: Nikos A
authors.initials: NA
authors.lastname: Kametas
authors.forename: Fionnuala
authors.initials: F
authors.lastname: McAuliffe
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Cacho-Zegarra
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000328:Adult; D000531:Altitude; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D010568:Peru; D011247:Pregnancy / Q000097:blood*; D012016:Reference Values
chemical_list: D018970:Insulin-Like Growth Factor Binding Protein 1