There is growing evidence that events occurring early in life, both before and after birth, are significantly associated with the risk of asthma, chronic obstructive pulmonary disease, and diminished lung function later in life. In fact, from conception to death, a series of continuous, dynamic gene–environment interactions determine 2 fundamental biological processes, namely, lung development and lung aging. Over 130 birth cohorts have been initiated in the last 30 years. Data from these cohorts have improved our understanding of the inception, progression, and persistency of asthma. In this review, we summarize the main data for the early life events proven to determine later development and persistence of asthma, such as maternal atopy and smoking, preterm birth/bronchopulmonary dysplasia, infections, nutrition, obesity, smoking, and other environmental exposures in childhood and adolescence.
While some of these factors are obviously impossible to prevent or eliminate, others have been proven to have a protective role, and current research is aimed optimizing them. Available prophylactic measures are also reviewed. In the case of environmental pollution, large scale political interventions successfully managed to decrease contamination levels, leading to improved lung function and lower asthma prevalence in the respective geographical areas.
Future research should focus on better understanding these complex interactions in order to develop and enhance effective preventive therapeutic measures.

Key words: Atopy, Asthma, Lung function, Pregnancy, Prematurity, Obstructive airway disease, Airway hyperreactivity