New study suggests role of natural and synthetic oestrogen in increasing risk of asthma 

Many studies suggest that an earlier age at menopause is more detrimental to a woman's health, leading to an increased risk for adverse health conditions such as heart disease, diabetes, osteoporosis, and depression, among others. However, a new study is linking a later age at natural menopause with a greater risk for asthma. 

Asthma is a common, chronic disease affecting more than 300 million people worldwide. The prevalence of asthma has been increasing over recent years. Adult-onset asthma is typically more severe and more difficult to treat than childhood asthma. 

Multiple studies have suggested a possible link between asthma and sex hormones. Most notable is the fact that adult-onset asthma is more common in women than men. In childhood, asthma is more prevalent in boys. After puberty, however, asthma occurs more often in girls. Women also tend to have more severe asthma and are less likely to have remission of the disease. 

Some studies have found a peak incidence of asthma at around 40 years, which is commonly the age of the menopause transition, whereas other studies found a peak at the average age at menopause, which is 51 years. Both natural oestrogen and synthetic oestrogen, such as used in hormone therapy, offer similar risk profiles. Women using hormone therapy were shown to have a 63% increased risk of asthma, whereas women who stopped hormone therapy were two times more likely to quit asthma treatment. Higher body mass index also is shown to be a risk factor for women, but not men, because fat produces oestrogen. 

Unfortunately, research on the association between menopause and asthma incidence is limited and has yielded conflicting results. That is why this newest study, based on 10 years of follow-up data from more than 14 000 postmenopausal women, was designed to investigate the association between the age at natural menopause and incidence of asthma in nonsmoking postmenopausal women. The study researchers found that women with early menopause (between 40 and 44 years of age) are at a reduced risk of asthma, which led them to suggest a role of oestrogen with asthma risk. 

"This study highlights sex-based differences in asthma, with women at a greater risk for asthma than men in adulthood. It also showed that women with later onset of menopause are at greater risk than those with early onset of menopause. Clinicians should be aware of this link and should monitor women with later age at natural menopause for asthma symptoms," said Dr Stephanie Faubion, medical director for The Menopause Society.