Early life risk factors for childhood asthma

Asthma is the most common chronic inflammatory disease in childhood. The disease often starts early in life with significant burden to children and their families and the healthcare system. An accumulating body of evidence indicates that both prenatal and early life exposures play uniquely important roles in asthma occurrence by modulating airway and immune functions. In addition, timing of such exposures during these periods is likely to modulate the growth and development of airways and immune functions. Extensive literature reviews were done to critically evaluate earlier work and to understand the mechanisms of the underlying associations. The findings of the analyses are encouraging. Using data from the southern California Children's Health study, both prenatal and early life exposures were found to be associated with asthma occurrence in children. Additionally, timing of exposure in infancy and family history of asthma modified some of these associations. Some of the associations were stronger for particular asthma phenotypes. Given the enormous burden from childhood asthma, further research is needed to assess the role of these and other genetic, epigenetic and environmental factors during critical windows of development across distinct asthma phenotypes. These findings also indicate that any intervention strategy to reduce the burden of asthma in young children should target prenatal and early life as a critical time point to modulate exposures to prevent disease occurrence.