THE EFFECT OF GENETIC AND ENVIRONMENTAL-FACTORS ON THE PREVALENCE OF ALLERGIC DISORDERS AT THE AGE OF 2 YEARS

The effect of genetic and environmental factors on the prevalence of a llergic disorders in early childhood was determined in a prospective f ollow-up study. Information was available on 1174 children at the age of 2 years. Two-hundred and seventy-five were considered to have an al lergic disorder. The prevalence varied from 3.2% for rhinitis to 10.9% for asthma. At 2 years 60 children reacted positively on skin-prick t est (SPT). Multivariate logistic regression analysis was used to obtai n adjusted odds ratios (95% confidence interval) for each factor. For asthma, positive family history, male sex, low birth-weight, maternal smoking and season of birth were significant risk factors. For eczema, positive family history was the only significant risk factor. For rhi nitis, lower socio-economic group and autumn birth were significant. M ale sex and low birth-weight were significant for skin test positivity . Positive family history and low birth-weight were significant risk f actors for any allergy. Low birth-weight was also a significant risk f or skin test reactivity to house dust mite. Genetic and environmental factors have a profound effect on the development of allergic disorder s in the first two years of life.