title: The effects of breastfeeding exclusivity on early childhood outcomes.
abstract: OBJECTIVE
  We examined the relationship between breastfeeding exclusivity and duration and children's health and cognitive outcomes at ages 2 and 4 years.
  
  
  METHODS
  We used the Early Childhood Longitudinal Study-Birth Cohort, a nationally representative sample of 10,700 children born in the United States in 2001. Parent interviews and child assessments were conducted in measurement waves at 9 months, 2 years, 4 years, and in kindergarten, with the focus on ages 2 and 4 years. We employed propensity scores as a means of adjusting for confounding involving observed characteristics.
  
  
  RESULTS
  Outcome analyses using propensity scores showed some small effects of breastfeeding on key outcomes at age 4 years but not at age 2 years. Effects appeared to be concentrated in reading and cognitive outcomes. Overall, we found no consistent evidence for dosage effects of breastfeeding exclusivity. Our sensitivity analyses revealed that a small amount of unobserved confounding could be responsible for the resulting benefits.
  
  
  CONCLUSIONS
  Our study revealed little or no effect of breastfeeding exclusivity and duration on key child outcomes.
authors.affiliation: Jade Marcus Jenkins is with the School of Education at the University of California, Irvine. At the time of the study, E. Michael Foster was with the Department of Health Care Organization and Policy, University of Alabama at Birmingham, Birmingham.
authors.forename: Jade Marcus
authors.initials: JM
authors.lastname: Jenkins
authors.forename: E Michael
authors.initials: EM
authors.lastname: Foster
mesh_terms: D001942:Breast Feeding / Q000379:methods* / Q000706:statistics & numerical data; D002657:Child Development; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D009048:Motor Skills; D057216:Propensity Score; D011932:Reading