Researchers have found that women with asthma appear more likely to have lower levels of testosterone than women who do not have the disease.
"Our study results suggest that the circulating sex hormones estradiol and 'free' (not attached to proteins) testosterone contribute to sex differences in asthma among adults," said study author Juan C. Celedón from the University of Pittsburgh in the US.
"Furthermore, obesity appears to modify the effect of such hormones on asthma in women and men," Celedón said.
For the finding published in the American Journal of Respiratory and Critical Care Medicine, researchers conducted a study to examine whether sex hormones are associated with asthma in adult men and women.
They also wanted to test whether any association varies between obese and non-obese individuals.
The research team analysed information from 9,238 adults, ages 18-79, who participated in the US National Health and Nutrition Examination Survey (NHANES) from 2013-16.
Overall, nine percent of the participants had asthma. Among women, the asthma rate was double that of men: 12.5 percent vs. 6.1 percent.
The study found that elevated levels of the sex hormones reduced the likelihood of asthma.
In women, levels of 'free' testosterone in the highest quartile compared to the lowest quartile were associated with 44 per cent lower odds of asthma.
According to the researchers, among obese women, levels of free testosterone in the highest quartile compared to the lowest quartile were associated with 41 per cent lower odds of asthma.
The study also found that, in women, levels of estradiol in the highest quartile compared to the lowest quartile were associated with 57 per cent lower odds of asthma.