title: Role of body mass index and gestational weight gain in breastfeeding outcomes.
abstract: OBJECTIVE
  This study determined whether high maternal prepregnancy body mass index (BMI) and/or excess gestational weight gain (GWG) is associated with reduced breastfeeding duration and earlier formula supplementation.
  
  
  METHODS
  A prospective longitudinal cohort of postpartum women (n=718), who were a subset of a larger randomized trial, was followed for 6 months postdelivery. We evaluated the relationship between BMI or BMI/GWG groups and timing of breastfeeding cessation and introduction of formula using Kaplan-Meier curves and log-rank tests. Then, we used multivariable Cox proportional hazards models to evaluate the relationship between BMI and BMI/GWG on these breastfeeding outcomes after controlling for potential confounding variables.
  
  
  RESULTS
  The expected relationships between high BMI and high BMI/GWG and poor breastfeeding outcomes were observed in Kaplan-Meier curves. However, after adjusting for relevant maternal and infant covariates in the Cox models, the differences became nonsignificant. Prepregnancy BMI category was not statistically associated with breastfeeding duration (p=0.06) or timing of formula introduction (p=0.15). Similarly, BMI and GWG in combination were not associated with duration (p=0.33) or timing of formula introduction (p=0.18). Mothers' intended breastfeeding duration and rating of the importance of breastfeeding remained the only significant modifiable predictors of breastfeeding outcomes in the final models.
  
  
  CONCLUSIONS
  Maternal BMI and GWG were not significantly associated with breastfeeding outcomes after adjusting for confounding variables. Mothers' plans for breastfeeding duration and the importance mothers assign to breastfeeding remain the optimal intervention points for lengthening breastfeeding duration and reducing formula supplementation.
authors.affiliation: Department of Kinesiology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. cjb25@psu.edu
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Bartok
authors.forename: Eric W
authors.initials: EW
authors.lastname: Schaefer
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Beiler
authors.forename: Ian M
authors.initials: IM
authors.lastname: Paul
mesh_terms: D000328:Adult; D015992:Body Mass Index; D001942:Breast Feeding / Q000706:statistics & numerical data; D005260:Female; D015438:Health Behavior; D006801:Humans; D007231:Infant, Newborn; D053208:Kaplan-Meier Estimate; D015999:Multivariate Analysis; D050177:Overweight; D010414:Pennsylvania; D011247:Pregnancy; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D013997:Time Factors; D015430:Weight Gain