Several studies have demonstrated an increased risk and increased effect of asthma in obesity. Studies have also shown gender variations.
A population-based analysis has shown a relationship between the use of hormonal contraceptives and asthma in women. Use of the oral contraceptive was associated with a reduced risk of physician-diagnosed asthma (OR 0.68, 95% CI 0.47-0.98) and receiving three or more asthma care episodes (OR 0.45, 95% CI 0.25-0.82). Evidence was equivocal for wheezing attacks. There was an increased risk (42-135%) of asthma in overweight and obese women who were not using contraception. The two conclusions from this study were that overweight and obese women may be at increased risk of asthma, and use of hormonal contraception may reduce asthma exacerbations and number of care episodes (Nwaru, 2015).
NWARU BI and SHEIKH A. Hormonal contraceptives and asthma in women of reproductive age: analysis of data from serial national Scottish Health Surveys. JRSM 2015;108(9):358-371.