title: Maternal cardiac function during pregnancy at high altitude.
abstract: OBJECTIVE
  To investigate the maternal cardiovascular adaptation in pregnancy at high altitude, compared with that at sea level.
  
  
  METHODS
  Cross sectional study.
  
  
  METHODS
  Two maternity units providing routine antenatal care: one at 4370 m above sea level (Cerro de Pasco, Peru) and one at sea level (Lima, Peru).
  
  
  METHODS
  We examined 175 pregnant women at 5-41 weeks of gestation and 16 non-pregnant controls resident at high altitude and 132 pregnant women and 18 non-pregnant controls at sea level.
  
  
  METHODS
  Two-dimensional and M-mode echocardiography of the left ventricle.
  
  
  METHODS
  Maternal cardiac output and left ventricular longitudinal and transverse systolic function indices.
  
  
  RESULTS
  Pregnancy at high altitude, compared with sea level, is associated with 11% lower birthweight and 31% lower maternal cardiac output, due to 15% lower stroke volume and 11% lower heart rate. The lower stroke volume was due to a lower preload and impaired longitudinal and transverse left ventricular systolic function. Mean arterial pressure was about 8% lower during pregnancy at high altitude versus sea level. Pregnant women at high altitude failed to expand their intravascular space to the same extent as the sea level group: cardiac output increased by 17%, left atrial diameter by 12% and end-diastolic diameter by 1% at high altitude versus 41%, 25% and 5%, respectively, at sea level.
  
  
  CONCLUSIONS
  Pregnancy at high altitude, compared with sea level, is characterised by lower cardiac output due to lower heart rate and lower stroke volume and reduced expansion of the maternal intravascular space compared with the non-pregnant state.
authors.affiliation: Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
authors.forename: Nikos A
authors.initials: NA
authors.lastname: Kametas
authors.forename: Fionnuala
authors.initials: F
authors.lastname: McAuliffe
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Krampl
authors.forename: John
authors.initials: J
authors.lastname: Chambers
authors.forename: Kypros H
authors.initials: KH
authors.lastname: Nicolaides
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D000531:Altitude; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D003430:Cross-Sectional Studies; D004452:Echocardiography / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D011247:Pregnancy / Q000502:physiology*; D013318:Stroke Volume / Q000502:physiology; D016216:Ultrasonography, Prenatal / Q000379:methods; D016277:Ventricular Function, Left / Q000502:physiology*