Background: Asthma is a chronic inflammatory airway disease that has a higher prevalence in boys than in girls before puberty and a higher prevalence in women than in men in adulthood. Because of the complexity of the disease, no single straightforward mechanism can explain the gender differences found in asthma.

Objective: This article reviews the effects of sex on the development and outcome of atopy and asthma.

Methods: English-language articles were identified by a PubMed database search from 1980 to 2007 using the terms asthma, gender, sex, hormones, and lung development.

Results: It is likely that hormonal changes and genetic susceptibility both contribute to the change in prevalence that occurs about the time of puberty. Severe asthma is also more predominant in females. In adulthood, women are more susceptible to the effects of smoking and more likely to develop asthma.

Conclusions: It is important to determine whether asthma is a social, cultural, hormonal, and/or genetic issue. A number of topics on gender differences in asthma development and progression require additional research. For example, the interaction of fetal lung development and hormonal factors needs to be studied because it has consequences throughout life. Genetic studies of asthma should be stratified by sex, because some polymorphisms are particularly related to asthma in females. Further studies should be conducted on hormone-gene interactions (eg, X-chromosome genes) in relation to asthma and atopy. In addition, cellular hormonal influences in asthma and atopy in relation to innate and acquired immunity in both sexes need to be examined. This would benefit patients not only with asthma but also with many other diseases that show gender differences in prevalence, severity, and treatment response. Animal models investigating observed gender differences in humans should focus on susceptibility to environmental and hormonal factors in relation to lung and immune development. Differences in treatment response in asthma need to be examined as well. Double-blind studies need to be stratified by sex, and treatment responses in females and males should be investigated separately. Furthermore, interaction between gender and behavioral change in relation to asthma development and management should be studied.