Breast-feeding and the risk of bronchial asthma in childhood: a systematic review with meta-analysis of prospective studies.
BACKGROUND
The protective effect of breast-feeding on the development of childhood asthma remains a matter of controversy. We conducted a systematic review of prospective studies that evaluated the association between exclusive breast-feeding during the first 3 months after birth and asthma.


METHODS
We searched the 1966-1999 MEDLINE database and reviewed reference lists of relevant articles to identify 12 prospective studies that met pre-stated inclusion criteria. Methodological aspects of the studies, duration and exclusivity of breast-feeding, and outcomes were assessed. Effect estimates were abstracted by the investigators, using a standardized approach.


RESULTS
The summary odds ratio (OR) for the protective effect of breast-feeding was 0.70 (95% CI 0.60 to 0.81). The effect estimate was greater in studies of children with a family history of atopy (OR = 0.52) than in studies of a combined population (OR = 0.73).


CONCLUSIONS
Exclusive breast-feeding during the first months after birth is associated with lower asthma rates during childhood. The effect, caused by immunomodulatory qualities of breast milk, avoidance of allergens, or a combination of these and other factors, strengthens the advantage of breast-feeding, especially if a family history of atopy is present.
Gdalevich
M
M
Department of General Pediatrics, Schneider Children's Medical Center of Israel, Petah Tiqvah, Israel.
Mimouni
D
D
Mimouni
M
M
D001249:Asthma / Q000517:prevention & control*; D001942:Breast Feeding; D006801:Humans; D007231:Infant, Newborn; D011446:Prospective Studies