Studies examining risk of asthma in offspring from asthmatic mothers and fathers.

In the Jan study asthma included probable asthmatics. In the Sheriff and Martel studies maternal asthma was asthma during pregnancy, while paternal asthma was defined by medical history. In the Johnson study parental asthma included hay fever and allergies. Medical doctor (MD) asthma  =  physician-diagnosed asthma. Quest MD asthma  =  physician-diagnosed asthma on questionnaire or by parents report.