Studies examining the sex differences in the epidemiology and morbidity patterns of asthma show that the rates of disease severity, healthcare utilisation, and poor quality of life are considerably higher in women than in men, and this has been attributed to endogenous and exogenous sex hormonal factors. Studies examining the impact of use of hormonal contraceptives on the risk of asthma and asthma-related conditions are few, yet findings are conflicting.

In the present study, the investigators utilize data from the Scottish Health Survey, a national representative sample, to investigate the associations between current use of hormonal contraceptives and the prevalence of self-reported doctor-diagnosed current asthma and wheezing symptoms in Scottish women. The investigators hypothesize that while current use of any hormonal contraceptives and combined oral pills are associated with higher prevalence of asthma and asthma outcomes, current use of progesterone-only contraceptives is not associated with asthma. A secondary aim of the current study is to examine whether there is evidence of any biological interaction between use of hormonal contraceptives and BMI in relation to the risk of asthma and asthma outcomes.

Inclusion Criteria:

• Non-pregnant
• Woman
• 16-45 years old

Exclusion Criteria:

• Pregnant
• Man
• Younger than 16 years or older than 45 years old

Non-pregnant women aged 16-45 years