title: Case-control study of breast milk calcium in mothers of children with and without nutritional rickets.
abstract: OBJECTIVE
  Despite similarly low calcium intakes and normal vitamin D status, only some Nigerian children develop nutritional rickets. We hypothesized that mothers with children who had developed rickets might have lower breast-milk calcium concentration than mothers with normal children and compared the breast-milk calcium concentration of mothers who had had children with rickets with those who had not (controls).
  
  
  METHODS
  We collected breast milk from 35 Nigerian mothers who had previously had children with nutritional rickets. For each case mother, we collected breast milk from three matched control mothers at the same stage of lactation (+/-4 weeks) who had had no children with rickets. Data were collected about parity, stage of lactation, and the infant's intake. The mother's bone density was measured.
  
  
  RESULTS
  The mean breast milk calcium concentration of mothers of children with rickets (4.30+/-1.24 mmol/L) was less than that of control mothers (4.65+/-1.03 mmol/L; P=0.034 in multivariate regression controlling for duration of lactation and resumption of menses). Forearm bone mineral content was significantly related to breast milk calcium concentration (r=0.20) after adjusting for height, weight, and bone area (P=0.028).
  
  
  CONCLUSIONS
  Reduced breast-milk calcium concentration may contribute to a reduced calcium intake in infancy and predispose children to nutritional rickets.
authors.affiliation: Department of Family Medicine, Jos University Teaching Hospital, Nigeria.
authors.forename: Tom D
authors.initials: TD
authors.lastname: Thacher
authors.forename: John M
authors.initials: JM
authors.lastname: Pettifor
authors.forename: Philip R
authors.initials: PR
authors.lastname: Fischer
authors.forename: Selina N
authors.initials: SN
authors.lastname: Okolo
authors.forename: Ann
authors.initials: A
authors.lastname: Prentice
mesh_terms: D002118:Calcium / Q000032:analysis*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D009035:Mothers; D009549:Nigeria; D012016:Reference Values; D012279:Rickets / Q000378:metabolism*
chemical_list: D002118:Calcium