Do Birth Season and Sex Affect Adult Lung Function as Early Life Factors?

Objectives: Although lung function decline is a normal ageing process, it can be potentiated by risk factors. However, the potential impact of early life factors on lung function decline has been scarcely studied. The aim of this study was to investigate the potential correlation between birth season and adult lung function. Methods: We enrolled 1008 South Korean patients (530 men and 478 women; age range, 40 80 years) who were hospitalized for urological surgery, irrespective of respiratory disease. All patients underwent the pulmonary function test before any surgery or procedure. Based on their birth season, the patients were divided into two groups (spring, summer, and fall vs. winter). Results: Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and FEV1 % predicted of men born in winter were lower than those of men born in other seasons. Univariate and multivariate analyses using linear regression models also showed that birth season was a significant predictive factor for FVC, FEV1, and FEV1 % predicted in men. However, birth season was not correlated with lung function in women. Among male ever-smokers, FEV1 and FEV1 % predicted were lower for men born in winter than for those born in other seasons. Conclusions: Unlike women, men born in winter had lower lung function than did men born in other seasons. These results suggest that birth season might be an early life factor that predicts airway function. Furthermore, birth season has different effects on adult lung function depending on the patient’s sex.