title: Breast-feeding influences thymic size in late infancy.
abstract: We have previously shown that breast-fed infants have a considerably larger thymus at 4 months than formula-fed infants. The aim of the present study was to investigate whether breast-feeding also influences the thymic size in late infancy. In a cohort of 50 infants, all being partially breast-fed when recruited at 8 months, ultrasound assessment of the thymic index (a volume estimate) was performed at both 8 and 10 months of age. At 10 months the thymic index was significantly higher in those still being breast-fed compared to infants who had stopped breast-feeding between 8 and 10 months of age (P=0.05). This difference became more significant when controlled for the influence of infectious diseases (P=0.03). In infants still breast-fed at 10 months there was a significant correlation between the number of breast-feeds per day and their thymic index (P=0.01). Conclusion The effect of breast-feeding on thymus size is likely to be caused by immune modulating factors in breast milk. Breast milk influences thymic size in late infancy.
authors.affiliation: Department of Radiology, Hvidovre Hospital, University of Copenhagen, Kettegårds Allé 30, DK-2650 Hvidovre, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Hasselbalch
authors.forename: M D
authors.initials: MD
authors.lastname: Engelmann
authors.forename: A K
authors.initials: AK
authors.lastname: Ersboll
authors.forename: D L
authors.initials: DL
authors.lastname: Jeppesen
authors.forename: K
authors.initials: K
authors.lastname: Fleischer-Michaelsen
mesh_terms: D001942:Breast Feeding; D004306:Dose-Response Relationship, Immunologic; D005260:Female; D006801:Humans; D007223:Infant; D007225:Infant Food; D008297:Male; D008895:Milk, Human / Q000276:immunology; D013950:Thymus Gland / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000276:immunology; D014463:Ultrasonography