This study evaluated the prevalence and risk factors for asthma,allergy and related symptoms;and breastfeeding patterns and durations for 5479 Beijing children aged 3–6.Parents of children in randomly selected kindergartens wrote responses to a questionnaire used previously.The study aimed to evaluate trends in the prevalence of asthma and related illnesses,and to determine whether"more"breastfeeding,defined as exclusive,>6 months,was associated with reduced prevalence.Asthma has increased in this age group between 1990 and 2011,with the steepest increase in the last 2–3 years.Of the total,14.2%(779)children were breastfed exclusively for>6 months.The efficacy of"more"breastfeeding was tested in a subset with two strong risk factors,positive family history(for asthma and/or allergy)and male gender."More"breastfeeding was found to be significantly protective(aOR 0.42,P<0.05)for this subset against Doctor-diagnosed asthma(D-asthma).Protection that did not reach statistical significance was also found for this subset against Wheeze ever,Cough at night,Rhinitis ever,Doctor-diagnosed rhinitis(D-rhinitis)and Eczema.The greatest protective effects were found for girls with no family history of asthma or allergy,reaching statistical significance for Wheeze ever(aOR 0.48,P<0.01),Cough at night(aOR 0.47,P<0.01),D-asthma(aOR 0.14,P<0.01)and Rhinitis ever(aOR 0.67,P<0.05)."More"breastfeeding was not consistently associated with either a protective or risk effect for Eczema.
