title: Breastfeeding versus formula-feeding and girls' pubertal development.
abstract: To examine the association of breastfeeding or its duration with timing of girls' pubertal onset, and the role of BMI as a mediator in these associations. A population of 1,237 socio-economically and ethnically diverse girls, ages 6-8 years, was recruited across three geographic locations (New York City, Cincinnati, and the San Francisco Bay Area) in a prospective study of predictors of pubertal maturation. Breastfeeding practices were assessed using self-administered questionnaire/interview with the primary caregiver. Girls were seen on at least annual basis to assess breast and pubic hair development. The association of breastfeeding with pubertal timing was estimated using parametric survival analysis while adjusting for body mass index, ethnicity, birth-weight, mother's education, mother's menarcheal age, and family income. Compared to formula fed girls, those who were mixed-fed or predominantly breastfed showed later onset of breast development [hazard ratios 0.90 (95 % CI 0.75, 1.09) and 0.74 (95 % CI 0.59, 0.94), respectively]. Duration of breastfeeding was also directly associated with age at onset of breast development (p trend = 0.008). Associations between breastfeeding and pubic hair onset were not significant. In stratified analysis, the association of breastfeeding and later breast onset was seen in Cincinnati girls only. The association between breast feeding and pubertal onset varied by study site. More research is needed about the environments within which breastfeeding takes place in order to better understand whether infant feeding practices are a potentially modifiable risk factor that may influence age at onset of breast development and subsequent risk for disease in adulthood.
authors.affiliation: School of Public Health, University of California, Berkeley, Berkeley, CA, USA, kale.aarti@gmail.com.
authors.forename: Aarti
authors.initials: A
authors.lastname: Kale
authors.forename: Julianna
authors.initials: J
authors.lastname: Deardorff
authors.forename: Maureen
authors.initials: M
authors.lastname: Lahiff
authors.forename: Cecile
authors.initials: C
authors.lastname: Laurent
authors.forename: Louise C
authors.initials: LC
authors.lastname: Greenspan
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hiatt
authors.forename: Gayle
authors.initials: G
authors.lastname: Windham
authors.forename: Maida P
authors.initials: MP
authors.lastname: Galvez
authors.forename: Frank M
authors.initials: FM
authors.lastname: Biro
authors.forename: Susan M
authors.initials: SM
authors.lastname: Pinney
authors.forename: Susan L
authors.initials: SL
authors.lastname: Teitelbaum
authors.forename: Mary S
authors.initials: MS
authors.lastname: Wolff
authors.forename: Janice
authors.initials: J
authors.lastname: Barlow
authors.forename: Anousheh
authors.initials: A
authors.lastname: Mirabedi
authors.forename: Molly
authors.initials: M
authors.lastname: Lasater
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Kushi
mesh_terms: D017668:Age of Onset; D015992:Body Mass Index; D001942:Breast Feeding; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D007223:Infant; D041943:Infant Formula; D009519:New York City; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011627:Puberty / Q000208:ethnology* / Q000502:physiology*; D012307:Risk Factors; D012495:San Francisco; D012959:Socioeconomic Factors; D016019:Survival Analysis