Objective To determine the association of perinatal and early life factors with asthma in children.
Method 787 children of two cohorts were investigated. Information was obtained at birth in 1994 and 1997/1998, and at school age, in 2004/2005 and 2005/2006, in the Brazilian cities of Ribeirão Preto and São Luís, respectively. Asthma was defined as the presence of whistling sounds or wheezing in the last 12 months associated with bronchial hyperresponsiveness measured by the methacholine bronchial challenge test. Two multiple logistic regression analysis models were carried out, one including only birth variables and the other also including early life variables.
Results The prevalence of asthma was 8.9%. In the final model, adjusted for birth and early life variables, females were protected against asthma (OR 0.49; 95% CI 0.26 to 0.94). Hospitalization due to pneumonia (OR 2.34; 95% CI 1.17 to 4.69) and a family history of asthma (OR 2.70; 95% CI 1.40 to 5.20) were found to be strongly associated with asthma. The presence of a cat in the house reduced the risk of asthma (OR 0.45; 95% CI 0.21 to 0.94) and father’s age of more than 35 years (OR 2.20; 95% CI 1.06 to 4.57) increased it. No statistically significant association was observed between low birth weight, intrauterine growth restriction, preterm birth, maternal smoking, parental socioeconomic characteristics and asthma.
Conclusion The perinatal variables analyzed did not interfere with the risk of asthma. A family history of asthma more than doubled the risk, possibly reflecting genetic factors. Infection during childhood seems to confer a greater risk of asthma, but the possibility of reverse causality cannot be ruled out.