Low birth weight and preterm delivery as risk factors for asthma and atopic dermatitis in young adult males

Gestational factors have been hypothesized to play a role in the susceptibi lity to asthma and atopic dermatitis. We examined whether fetal growth was associated with asthma and atopic dermatitis separately in a population of 4,795 male conscripts born between 1973 and 1975 in Denmark. The prevalence of asthma was 4.7%. The prevalence odds ratio of asthma in conscripts with a birth weight below 2,501 g was 1.5 (95% confidence interval = 0.7-3.1) c ompared with conscripts with a birth weight of 3,001-3,500 g, adjusted for gestational age and potential confounders. The adjusted prevalence odds rat io among conscripts born before 34 gestational weeks was 0.8 (95% confidenc e interval = 0.3-2.0) compared with conscripts born at term. The prevalence of atopic dermatitis was 1.0%. The prevalence odds ratio of atopic dermati tis among those with a birth weight below 2,501 g was 3.0 (95% confidence i nterval = 0.8-11.9) compared with those whose birth weight was between 3,00 1 and 3,500 g. Men whose gestational age had been below 34 weeks had an adj usted prevalence odds ratio of 0.3 (95% confidence interval = 0.0-3.1). The se findings indicate that fetal growth retardation rather than preterm deli very of male infants is the main gestational factor underlying the associat ions but does not explain the apparent increase over time of asthma or atop ic diseases.