Birth weight, education, environment, and lung function at school age: a community study in an alpine area

Our aim was to assess the effect of birth weight, gestational age, predispositions, education, housing and environmental factors on indices of lung function and to evaluate selective interactions among the main predictors. We studied schoolchildren (aged 7.5-12 yrs) in a cross-sectional survey of 13 small alpine communities in Tyrol (Austria). Data were collected retrospectively from self-administered questionnaires (n=796, 85% response), public records and lung function testing (n=752, 80% response). In the multivariate analysis it was found that a low birth weight (LBW), a low length of maternal education, a smaller gestational age, and a larger family size were all negatively associated with most lung function measures. Additionally, three significant interactions (birth weight with maternal education, birth weight with gestational age; and birth weight with family size) were observed. This implies that children of an LBW with mothers having a low level of education have a forced expiratory volume in one second (FEV1) value 148 mL lower than average values. Children born at term with an LBW have a 140 mL lower mean FEV1 value, and children of LBW from larger families display a 123 mL lower mean estimate of FEV1. However, subgroups were small (n=26, 17 and 27, respectively). The results support low birth weight as a significant predictor of decreased lung function at school age. However, the size and the direction of the association may differ depending on the levels of the interacting variables.