title: Association between total duration of breastfeeding and iron deficiency.
abstract: OBJECTIVE
  To determine whether there is an association between the total breastfeeding duration and iron stores, iron deficiency, and iron deficiency anemia in healthy urban children.
  
  
  METHODS
  A cross-sectional study of healthy children, aged 1 to 6 years, seen for primary health care between December 2008 and July 2011 was conducted through the TARGet Kids! practice-based research network. Univariate and adjusted regression analyses were used to evaluate an association between total breastfeeding duration and serum ferritin, iron deficiency, and iron deficiency anemia.
  
  
  RESULTS
  Included were 1647 healthy children (median age 36 months) with survey, anthropometric, and laboratory data. An association was found between increasing duration of breastfeeding and lower serum ferritin (P = .0015). Adjusted logistic regression analysis revealed the odds of iron deficiency increased by 4.8% (95% confidence interval: 2%-8%) for each additional month of breastfeeding. Exploratory analysis suggested an increasing cumulative probability of iron deficiency with longer total breastfeeding duration with an adjusted odds ratio of 1.71 (95% confidence interval: 1.05-2.79) for iron deficiency in children breastfed over versus under 12 months of age. The relationship between total breastfeeding duration and iron deficiency anemia did not meet statistical significance.
  
  
  CONCLUSIONS
  Increased total breastfeeding duration is associated with decreased iron stores, a clinically important association warranting additional investigation.
authors.affiliation: Department of Pediatrics, St Michael's Hospital, Toronto ON M5B 1W8 Canada. jonathon.maguire@utoronto.ca
authors.forename: Jonathon L
authors.initials: JL
authors.lastname: Maguire
authors.forename: Leila
authors.initials: L
authors.lastname: Salehi
authors.forename: Catherine S
authors.initials: CS
authors.lastname: Birken
authors.forename: Sarah
authors.initials: S
authors.lastname: Carsley
authors.forename: Muhammad
authors.initials: M
authors.lastname: Mamdani
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Thorpe
authors.forename: Gerald
authors.initials: G
authors.lastname: Lebovic
authors.forename: Marina
authors.initials: M
authors.lastname: Khovratovich
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Parkin
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D018798:Anemia, Iron-Deficiency / Q000453:epidemiology / Q000209:etiology* / Q000503:physiopathology; D000886:Anthropometry; D001942:Breast Feeding / Q000009:adverse effects* / Q000379:methods; D002648:Child; D002675:Child, Preschool; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007501:Iron / Q000097:blood* / Q000378:metabolism; D016014:Linear Models; D008297:Male; D015999:Multivariate Analysis; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors
chemical_list: D007501:Iron
keywords: breastfeeding duration; cross-sectional studies; iron deficiency; serum ferritin