title: Hemoglobin levels and anemia evaluation during pregnancy in the highlands of Tibet: a hospital-based study.
abstract: BACKGROUND
  Anemia is regarded as a major risk factor for unfavorable pregnancy outcomes, but there have been no previous studies describing the pattern of hemoglobin concentration during pregnancy in Tibet and the relationship between altitude and Hb concentration in the pregnant women living in Tibet still has not been clearly established. The main objectives of this study were to study the hemoglobin levels and prevalence of anemia among pregnant women living in the highlands of Tibet and to evaluate potential associations of hemoglobin and anemia with women's characteristics.
  
  
  METHODS
  The hospital-based study was conducted in 380 pregnant women. Their blood samples were tested and related sociodemographic information was collected. Multiple linear regression model and multiple logistic regression model were used to assess the association of pregnant women's characteristics with hemoglobin level and the occurrence of anemia. Centers for Disease Control (CDC), Dirren et al. and Dallman et al. methods were used to adjust the hemoglobin measurements based on altitude for estimating the prevalence of anemia.
  
  
  RESULTS
  The mean hemoglobin concentration was 127.6 g/L (range: 55.0-190.0 g/L). Prevalence rate of anemia in this study was 70.0%, 77.9% and 41.3%, respectively for three altitude-correction methods for hemoglobin (CDC method, Dirren et al. method, and Dallman et al. method). Gestational age, ethnicity, residence and income were significantly associated with the hemoglobin concentration and prevalence of anemia in the study population. Specially, the hemoglobin concentration of pregnant women decreased with increase in gestational age.
  
  
  CONCLUSIONS
  The hemoglobin level was low and prevalence rate of anemia was high among pregnant women in Lhasa, Tibet. Gestational age, ethnicity, residence and income were found to be significantly associated with the hemoglobin level and the occurrence of anemia in the study population.
authors.affiliation: Department of Epidemiology and Health Statistics, Xi'an Jiaotong University College of Medicine, Xi'an, PR China. tjxxyy@163.com
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xing
authors.forename: Hong
authors.initials: H
authors.lastname: Yan
authors.forename: Shaonong
authors.initials: S
authors.lastname: Dang
authors.forename: Bianba
authors.initials: B
authors.lastname: Zhuoma
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhou
authors.forename: Duolao
authors.initials: D
authors.lastname: Wang
mesh_terms: D000328:Adult; D000740:Anemia / Q000097:blood* / Q000208:ethnology; D005260:Female; D005865:Gestational Age; D006760:Hospitalization / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D016014:Linear Models; D011159:Population Surveillance; D011247:Pregnancy; D011250:Pregnancy Complications, Hematologic / Q000453:epidemiology*; D015995:Prevalence; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012424:Rural Population / Q000706:statistics & numerical data; D012959:Socioeconomic Factors; D018609:Tibet / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data; D016387:Women's Health