title: Does breastfeeding duration decrease child obesity? An instrumental variables analysis.
abstract: Many studies have documented that breastfeeding is associated with a significant reduction in child obesity risk. However, a persistent problem in this literature is that unobservable confounders may drive the correlations between breastfeeding behaviors and child weight outcomes.
  
  
  
  This study examines the effect of breastfeeding practices on child weight outcomes at age 2.
  
  
  
  This study relied on population-based data for all births in Oregon in 2009 followed for two years. We used instrumental variables methods to exploit variations in breastfeeding by mothers immediately after delivery and the degree to which hospitals encouraged mothers to breastfeed in order to isolate the effect of breastfeeding practices on child weight outcomes.
  
  
  
  We found that for every extra week that the child was breastfed, the likelihood of the child being obese at age 2 declined by 0.82% [95% CI -1.8% to 0.1%]. Likewise, for every extra week that the child was exclusively breastfed, the likelihood of being obese declined by 0.66% [95% CI -1.4 to 0.06%]. While the magnitudes of effects were modest and marginally significant, the results were robust in a variety of specifications.
  
  
  
  The results suggest that hospital practices that support breastfeeding may influence childhood weight outcomes.
authors.affiliation: Stanford University, School of Medicine, Palo Alto, CA, USA.
authors.forename: S
authors.identifier: 0000-0003-4557-7156
authors.initials: S
authors.lastname: Modrek
authors.affiliation: Stanford University, School of Medicine, Palo Alto, CA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Basu
authors.affiliation: Sanford School of Public Policy, Duke University, Durham, NC, USA.
authors.forename: M
authors.initials: M
authors.lastname: Harding
authors.affiliation: University of California, San Francisco, San Francisco, CA, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: White
authors.affiliation: Cambridge Health Alliance, Somerville Hospital, Somerville, MA, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Bartick
authors.affiliation: School of Medicine, Stanford University, Palo Alto, CA, USA.
authors.forename: E
authors.initials: E
authors.lastname: Rodriguez
authors.affiliation: Oregon Health & Science University, Portland, OR, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Rosenberg
mesh_terms: D001835:Body Weight / Q000502:physiology*; D001942:Breast Feeding; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009035:Mothers; D009922:Oregon; D050177:Overweight / Q000517:prevention & control*; D063766:Pediatric Obesity / Q000517:prevention & control*; D013997:Time Factors
keywords: Breastfeeding; child obesity; hospital practices; instrumental variable analysis