Childhood asthma most often starts before school age. During puberty, many children – especially boys – experience improvement, but later in life the symptoms of asthma often recur. During early life, boys more frequently have asthma; after 10 years of age, however, girls more frequently develop asthma, often with greater severity. However, with modern asthma treatment and care, most asthmatic individuals are able to lead a normal, healthy life. The lifetime risk of asthma is approximately 35%, with most cases occurring early in life, and many requiring lifelong medical follow-up and medication, and thus having an impact on health costs. Early childhood asthma and, in particular, severe childhood asthma increase the risk of chronic airway obstruction in adult life.