Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster randomised trial

Objective To assess whether exclusive and prolonged breast feeding reduces the risk of childhood asthma and allergy by age 6.5 years.Design Cluster randomised trial.Setting 31 Belarussian maternity hospitals and their affiliated polyclinics.Participants A total of 17 046 mother-infant pairs were enrolled, of whom 13 889 (81.5%) were followed up at age 6.5 years.Intervention Breastfeeding promotion intervention modelled on the WHO/UNICEF baby friendly hospital initiative.Main outcome measures International study of asthma and allergies in childhood (ISAAC) questionnaire and skin prick tests of five inhalant antigens.Results The experimental intervention led to a large increase in exclusive breast feeding at 3 months (44.3% v 6.4%; P