title: Reference values and predictors of white blood cell subset counts: a cross-sectional study among HIV seronegative pregnant women in Zimbabwe.
abstract: OBJECTIVE
  To identify predictors and develop reference values of white blood cell subset counts for pregnant black women in Zimbabwe.
  
  
  METHODS
  In this cross-sectional study, multiple linear regression (MLR) analysis was employed to assess the relationship of WBC subset counts with age, gestational age, gravidity, season, serum retinol, beta-carotene, ferritin, folate and alpha-1 antichymotrypsin among 998 women 22-35 weeks pregnant attending antenatal care (ANC) in Harare, Zimbabwe.
  
  
  RESULTS
  Mean age was 24.0 (95% CI; 23.6-24.4), range 14-45 years. The mean gestational age was 29.2 (95% CI; 29.0-29.4), range 22-35 weeks. Median gravidity was 2, range 1-9. Predictors of neutrophil counts were gestational age, season and serum ferritin, the latter in interaction with gravidity (interaction, p = 0.016). Mean lymphocyte count was 0.13 x 10(9)cells/l higher in gravida >4 than gravida 1-3, and 0.35 x 10(9)cells/l higher in the late rainy than other seasons. Predictors of monocyte counts were gestational age, serum folate and season, while eosinophil counts declined with advancing gestation. Reference values adjusted or unadjusted for identified predictors were different from those of pregnant and non-pregnant white women reported in the literature.
  
  
  CONCLUSIONS
  Gravidity, season and micronutrient status influence WBC counts during pregnancy and therefore are of physiological and clinical importance. WBC reference values in the literature were not applicable obviating the need for local reference values.
authors.affiliation: Blair Research Laboratory, Ministry of Health and Child Welfare, PO Box CY573, Harare, Zimbabwe. gomo@blair.co.zw
authors.forename: Exnevia
authors.initials: E
authors.lastname: Gomo
authors.forename: Birgitte J
authors.initials: BJ
authors.lastname: Vennervald
authors.forename: Patricia D
authors.initials: PD
authors.lastname: Ndhlovu
authors.forename: Pernille
authors.initials: P
authors.lastname: Kaestel
authors.forename: Norman Z
authors.initials: NZ
authors.lastname: Nyazema
authors.forename: Henrik
authors.initials: H
authors.lastname: Friis
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging; D003430:Cross-Sectional Studies; D004804:Eosinophils; D005260:Female; D005293:Ferritins / Q000097:blood; D005492:Folic Acid / Q000097:blood; D005865:Gestational Age; D018023:HIV Seronegativity; D006801:Humans; D007958:Leukocyte Count; D016014:Linear Models; D018655:Lymphocyte Count; D008875:Middle Aged; D009000:Monocytes; D009504:Neutrophils; D010298:Parity; D011247:Pregnancy; D012016:Reference Values; D012621:Seasons; D014801:Vitamin A / Q000097:blood; D015030:Zimbabwe; D000514:alpha 1-Antichymotrypsin / Q000097:blood; D019207:beta Carotene / Q000097:blood
chemical_list: D000514:alpha 1-Antichymotrypsin; D019207:beta Carotene; D014801:Vitamin A; D005293:Ferritins; D005492:Folic Acid