Fetal growth rather than prematurity determines lung function in children with asthma

Abstract Background and Objective Preterm birth or fetal growth has been associated with reduced lung function and asthma during childhood in the general population. We aimed to elucidate whether prematurity or fetal growth has a significant influence on lung function or symptoms in children with stable asthma. Methods We included children with stable asthma who participated in the Korean childhood Asthma Study cohort. Asthma symptoms were determined by asthma control test (ACT). Percent predicted values of pre‐ and post‐bronchodilator (BD) lung function including forced expiratory volume in 1 second (FEV 1 ), forced vital capacity (FVC), and forced expiratory flow at 25%–75% of FVC (FEF 25%–75% ) were measured. Lung function and symptoms were compared according to the history of preterm birth and birth weight (BW) for gestational age (GA). Results The study population consisted of 566 children (age range: 5–18 years). There were no significant differences in lung function and ACT between preterm and term subjects. We observed no significant difference in ACT but significant differences were observed in pre‐ and post‐BD FEV 1 , pre‐ and post‐BD FVC, and post‐BD FEF 25%–75% according to BW for GA in total subjects. Two‐way ANOVA revealed that BW for GA rather than prematurity was a significant determining factor for pre‐ and post‐BD lung function. After regression analysis, BW for GA was still a significant determining factor of pre‐ and post‐BD FEV 1 and pre‐ and post‐BD FEF 25%–75% . Conclusion Fetal growth rather than prematurity appears to have a significant effect on lung function in children with stable asthma.