title: Exposure to Tobacco Metabolites via Breast Milk and Infant Weight Gain: A Population-Based Study.
abstract: BACKGROUND
  Although the immutable benefits of breastfeeding are well documented, information on the potential consequences of exposure to tobacco metabolites specifically via breastfeeding is sparse.
  
  
  OBJECTIVE
  The aim was to conduct the first study of the association between exposure to tobacco metabolites specifically through breastfeeding and infant weight gain.
  
  
  METHODS
  We used historical data from the US Collaborative Perinatal Project. Mothers were classified as nonsmokers, light smokers (1-19 cigarettes/day), and heavy (20+ cigarettes/day) smokers. In-hospital feeding type was observed during a nursery stay after delivery. We conducted stratified analyses among average-for-gestational-age (AGA; N = 23 571) and small-for-gestational-age (SGA; N = 2552) infants. We isolated the effect of exposure to tobacco metabolites specifically through breastfeeding.
  
  
  RESULTS
  Overall, maternal smoking was associated with change in weight-for-length z-score in a dose-response manner. Change in weight z-score was most pronounced among SGA infants of heavy smokers (breastfed: 0.53; 95% confidence interval [CI], 0.12-0.94; formula fed: 0.17; 95% CI, 0.03-0.30). Exposure to tobacco metabolites specifically through breastfeeding was not associated with additional weight gain among AGA infants. Among the much smaller sample of SGA infants, exposure specifically through breastfeeding was associated with marginally significant additional weight gain (0.46; 95% CI, 0.00-0.91) among infants of heavy smokers.
  
  
  CONCLUSIONS
  Our findings are in accord with recommendations by health agencies for smokers to breastfeed. However, SGA infants exposed to tobacco metabolites via breastfeeding by heavy smokers appear to gain weight more rapidly than other infants. Practical implications of our findings are discussed.
authors.affiliation: Maternal and Child Health Program, School of Public Health, University of Maryland, College Park, MD, USA Department of Epidemiology and Biostatistics, School of Public Health, University of Maryland, College Park, MD, USA Department of Epidemiology, School of Medicine, University of Maryland, Baltimore, MD, USA Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA shenassa@umd.edu.
authors.forename: Edmond D
authors.initials: ED
authors.lastname: Shenassa
authors.affiliation: Division of Behavioral Medicine, Department of Pediatrics, State University of New York at Buffalo, Buffalo, NY, USA.
authors.forename: Xiaozhong
authors.initials: X
authors.lastname: Wen
authors.affiliation: Department of Family and Community Health, University of Maryland, Baltimore, MD, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Braid
mesh_terms: D000328:Adult; D001724:Birth Weight; D001942:Breast Feeding; D002657:Child Development / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D008425:Maternal Behavior; D008895:Milk, Human / Q000737:chemistry*; D009538:Nicotine / Q000009:adverse effects*; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects*; D015430:Weight Gain / Q000187:drug effects*
chemical_list: D009538:Nicotine
keywords: breastfeeding; infancy; maternal smoking; rapid weight gain; weight