The study done by researchers at the Brigham and Women's Hospital and Harvard Medical School has shown that boys grow out asthma when they reach adulthood.

Researchers analyzed the data collected from 1,041 children, aged 5 to 12 years with mild to moderate persistent asthma. These children were given different doses of methacholine depending of severity of the asthma.  Annual spirometry tests with methacholine to measure the responsiveness of their airways were done. Researchers found that amount of methacholine required for boys increased with the passage of the time while dosage remained standard for girls for more time. This study showed that asthma was getting better in boys.

Researchers found out that until the age of 11 years, airway hyper-reactivity decreased in both boys and girls and the average twitchiness was about the same in both sexes. But starting around puberty, the level of airway hyper-reactivity remained fairly constant in girls and was more severe relative to that seen in boys.

Researchers added that further research is required to find out how difference in sex is related to asthma. Lead author Dr Kelan Tantisira said that the present study point to intriguing potential mechanisms to explain the gender differences in asthma incidence and severity. Especially intriguing is that the differences in gender begin at the time of transition into early puberty.