title: Breast-feeding and childhood-onset type 1 diabetes: a pooled analysis of individual participant data from 43 observational studies.
abstract: OBJECTIVE
  To investigate if there is a reduced risk of type 1 diabetes in children breastfed or exclusively breastfed by performing a pooled analysis with adjustment for recognized confounders.
  
  
  METHODS
  Relevant studies were identified from literature searches using MEDLINE, Web of Science, and EMBASE. Authors of relevant studies were asked to provide individual participant data or conduct prespecified analyses. Meta-analysis techniques were used to combine odds ratios (ORs) and investigate heterogeneity between studies.
  
  
  RESULTS
  Data were available from 43 studies including 9,874 patients with type 1 diabetes. Overall, there was a reduction in the risk of diabetes after exclusive breast-feeding for >2 weeks (20 studies; OR = 0.75, 95% CI 0.64-0.88), the association after exclusive breast-feeding for >3 months was weaker (30 studies; OR = 0.87, 95% CI 0.75-1.00), and no association was observed after (nonexclusive) breast-feeding for >2 weeks (28 studies; OR = 0.93, 95% CI 0.81-1.07) or >3 months (29 studies; OR = 0.88, 95% CI 0.78-1.00). These associations were all subject to marked heterogeneity (I(2) = 58, 76, 54, and 68%, respectively). In studies with lower risk of bias, the reduced risk after exclusive breast-feeding for >2 weeks remained (12 studies; OR = 0.86, 95% CI 0.75-0.99), and heterogeneity was reduced (I(2) = 0%). Adjustments for potential confounders altered these estimates very little.
  
  
  CONCLUSIONS
  The pooled analysis suggests weak protective associations between exclusive breast-feeding and type 1 diabetes risk. However, these findings are difficult to interpret because of the marked variation in effect and possible biases (particularly recall bias) inherent in the included studies.
authors: School of Medicine and Dentistry, Queen’s University Belfast, Belfast, UK. c.cardwell@qub.ac.uk
authors: Chris R
authors: CR
authors: Cardwell
authors: Lars C
authors: LC
authors: Stene
authors: Johnny
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authors: Ludvigsson
authors: Joachim
authors: J
authors: Rosenbauer
authors: Ondrej
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authors: Cinek
authors: Jannet
authors: J
authors: Svensson
authors: Francisco
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authors: Perez-Bravo
authors: Anjum
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authors: Memon
authors: Suely G
authors: SG
authors: Gimeno
authors: Emma J K
authors: EJ
authors: Wadsworth
authors: Elsa S
authors: ES
authors: Strotmeyer
authors: Michael J
authors: MJ
authors: Goldacre
authors: Katja
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authors: Radon
authors: Lee-Ming
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authors: Chuang
authors: Roger C
authors: RC
authors: Parslow
authors: Amanda
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authors: Chetwynd
authors: Kyriaki
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authors: Karavanaki
authors: Girts
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authors: Brigis
authors: Paolo
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authors: Pozzilli
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authors: Schober
authors: Gabriele
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authors: Devoti
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authors: Sipetic
authors: Geir
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authors: Joner
authors: Constantin
authors: C
authors: Ionescu-Tirgoviste
authors: Carine E
authors: CE
authors: de Beaufort
authors: Kirsten
authors: K
authors: Harrild
authors: Victoria
authors: V
authors: Benson
authors: Erkki
authors: E
authors: Savilahti
authors: Anne-Louise
authors: AL
authors: Ponsonby
authors: Mona
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authors: Salem
authors: Samira
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authors: Rabiei
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authors: CC
authors: Patterson
mesh_terms: D000293:Adolescent; D001942:Breast Feeding; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male