Atopy risk factors at birth and in adulthood [Fatores de risco para atopia no nascimento e na idade adulta]

Objective: to study the association between atopy and variables such as weight,length,and socioeconomic level at birth and in young adulthood. methods: a total of 2,063 subjects were investigated in a prospective birth cohort study of individuals born in ribeirão preto,brazil,in 1978/1979,and examined at the age of 23-25 years. skin prick tests (spt) for eight common allergens in brazil were performed. subjects with a wheal reaction ≥ 3 mm to one or more of the eight allergens tested were considered to be atopic. we used the log-binomial model (generalized linear model) in order to assess the association between atopy and birth or adult variables. results: the prevalence of positive spt was 47.6%. male gender was associated with an increased risk of atopy (relative risk [rr] = 1.18; 95% confidence interval [95%ci] 1.07-1.30). low level of schooling was a protective factor against atopy,with a rr = 0.74; 95%ci 0.62-0.89. living with a smoker in childhood was also associated with lower risk of atopy (rr = 0.87; 95%ci 0.79-0.96). birth weight,length and order,maternal age,and intrauterine growth restriction were not associated with positive spt. conclusions: this study showed that male gender was associated with an increased risk of atopy. low socioeconomic status,assessed by low level of schooling,was a protective factor against atopy. these data agree with the hygiene hypothesis. copyright © 2011 by sociedade brasileira de pediatria.