Prematurity as a risk factor for asthma in preadolescent children.

Information on long-term respiratory symptoms in prematurely born children is scanty. We studied an unselected population of 9- to 11-year-old schoolchildren. A self-administered questionnaire was distributed to the parents. Children underwent lung function testing, cold air challenge, and skin prick tests. A gestational age < 37 weeks in children with a birth weight < or = 2500 gm was reported by 5% of the parents. Premature girls had significantly more current asthma (odds ratio (OR) 2.6; 95% confidence interval (CI) 1.4, 4.7; p < 0.05), recurrent wheezing (OR 1.7; 95% CI 1.1, 2.7; p < 0.001), recurrent shortness of breath (OR 2.4; 95% CI 1.5, 3.9; p < 0.001), and frequent cough with exercise (OR 1.8; 95% CI 1.1, 2.9; p < 0.05) than term girls, especially if they required mechanical ventilation after birth. No such differences could be shown in boys. More prematurely born children who required mechanical ventilation (OR 3.7; 95% CI 2.2, 6.4; p < 0.0001) had a family history of asthma than children born at term. Significant decrements could be demonstrated for different measurements of lung function in premature girls. These results remained significant after control for confounders in a multivariate regression analysis. No difference was found between groups for bronchial hyperresponsiveness to cold, dry air or for atopic sensitization. We conclude that a family history of asthma may predispose premature children to more severe respiratory disease. Respiratory symptoms and decrements in lung function seen in girls may reflect abnormalities of lung function in survivors of severe neonatal respiratory disease.