Effects of exposure to paternal environmental tobacco smoke, respiratory disease requiring hospitalization, and breast feeding during infancy on lung functioning

Effects of paternal environmental tobacco smoke (PETS) exposure, hospitalization for respiratory disease, and breast feeding on lung function were investigated through independent statistical modeling of forced vital capacity (FVC), forced expiratory volume at 1 second (FEV1), and their ratio (%FEV1/FVC). Spirometric data and measurements of subject height, weight, and age were collected from a cohort of 3,436 Chinese school children in the first through fourth grades over a 3.5 year study period in four Chinese cities. A parental survey of data including subject demographics and the health and exposure histories of the children and their parents was administered prior to testing. Analysis was restricted to subjects with a parental survey and at least one spirometric assessment. Gender-specific random coefficient models were developed independently for each spirometric outcome. Estimates of lung function, expressed as percentage differences between the PETS exposed and unexposed, were compared at central height, weight, and age values. Effects of early (conception forwards ending prior to the survey), recent (subsequent to conception), and continuous (from conception forwards and ongoing at the parental survey) measures of PETS exposure on lung function were assessed, as were effects of respiratory disease requiring hospitalization and breast feeding during infancy. Effects of any PETS exposure and all the pack-years the father smoked were examined in additional analyses. Full models (adjusted for all potential confounders) and less comprehensive models (adjusted for only city and district) were fit in analyses. Continuous PETS exposure had a significant obstructive effect on lung function in the girls. Respiratory disease requiring hospitalization had a significant negative effect on the lung growth in the boys in less comprehensive models. The statistical significance but not the magnitude of the effect was explained with further adjustment. Breast feeding during infancy had a non-beneficial effect which was not statistically significant effect on the lung function of the girls. Estimated percentage differences in FVC for breast fed versus non-breast fed differed significantly between genders. Gender differences in lung function obtained in analyses may reflect differences in lung physiology as well as differential rates of somatic development in Chinese children.