title: Maternal hemoglobin concentration and adverse pregnancy outcomes at low and moderate altitudes in Peru.
abstract: OBJECTIVE
  To identify associations of maternal hemoglobin (Hb) with perinatal outcomes at low and moderate altitudes in Peru.
  
  
  METHODS
  Study of records with sequential information using perinatal database system. The study included 295 651 pregnant women with their products. Using multiple logistic regression analysis, we estimated the probability of stillbirths, preterm and small for gestational age (SGA) births associated with maternal Hb levels at low (0-1999 m) and moderate altitudes (2000-2999 m).
  
  
  RESULTS
  Maternal Hb decreased as pregnancy progressed from first to third trimester at both altitudes. Hb was higher at moderate than at low altitude (p < 0.001). Risks for stillbirths increased with low maternal Hb (odds ratio [OR]: 1.39 for Hb 9-9.9; OR: 1.84 for Hb 8-8.9; OR: 3.25 for Hb 7-7.9; and OR: 7.8 for Hb <7 g/dl); with Hb higher than 14.5 g/dl (OR: 1.31) and with altitudes ≥ 2000 m (OR: 1.2). High preterm rates were also observed with low Hbs (OR: 1.16 for Hb 9-9.9; OR: 1.64 for Hb 8-8.9; OR: 2.25 for Hb 7-7.9; and OR:2.87 for Hb<7 g/dl) and with Hb higher than 14.5 g/dl (OR: 1.14). High SGA rates were observed in neonates with maternal Hb of 7-7.9 (OR: 1.35) and <7 g/dl (OR:1.57), and higher than 14.5 g/dl (OR: 1.33), and with moderate altitudes (OR: 1.12). The cut-off points for lower risks of stillbirth and preterm births was 10 g/dl, and for SGA 9 g/dl of hemoglobin.
  
  
  CONCLUSIONS
  Low and high maternal Hb levels and moderate altitude were independent risk factors for adverse perinatal outcomes.
authors: Department of Biological and Physiological Sciences, Lima, Peru. Gustavo.gonzales@upch.pe
authors: Gustavo F
authors: GF
authors: Gonzales
authors: Vilma
authors: V
authors: Tapia
authors: Manuel
authors: M
authors: Gasco
authors: Carlos E
authors: CE
authors: Carrillo
mesh_terms: D000531:Altitude; D000740:Anemia / Q000453:epidemiology; D005260:Female; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D010568:Peru; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000453:epidemiology; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000453:epidemiology*; D050497:Stillbirth / Q000453:epidemiology*
chemical_list: D006454:Hemoglobins