title: Duration of exclusive breast-feeding: introduction of complementary feeding may be necessary before 6 months of age.
abstract: The WHO recommends exclusive breast-feeding for the first 6 months of life. At present, <2 % of mothers who breast-feed in the UK do so exclusively for 6 months. We propose the testable hypothesis that this is because many mothers do not provide sufficient breast milk to feed a 6-month-old baby adequately. We review recent evidence on energy requirements during infancy, and energy transfer from mother to baby, and consider the adequacy of exclusive breast-feeding to age 6 months for mothers and babies in the developed world. Evidence from our recent systematic review suggests that mean metabolisable energy intake in exclusively breast-fed infants at 6 months is 2.2-2.4 MJ/d (525-574 kcal/d), and mean energy requirement approximately 2.6-2.7 MJ/d (632-649 kcal/d), leading to a gap between the energy provided by milk and energy needs by 6 months for many babies. Our hypothesis is consistent with other evidence, and with evolutionary considerations, and we briefly review this other evidence. The hypothesis would be testable in a longitudinal study of infant energy balance using stable-isotope techniques, which are both practical and valid.
authors.affiliation: Division of Developmental Medicine, University of Glasgow, Yorkhill Hospitals, Glasgow, G3 8SJ, UK. jjr2y@clinmed.gla.ac.uk
authors.forename: John J
authors.initials: JJ
authors.lastname: Reilly
authors.forename: Jonathan C K
authors.initials: JC
authors.lastname: Wells
mesh_terms: D000367:Age Factors; D001903:Bottle Feeding; D001942:Breast Feeding; D002149:Energy Intake; D004734:Energy Metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007774:Lactation / Q000502:physiology; D008297:Male; D009751:Nutritional Requirements; D011634:Public Health; D013997:Time Factors