Female hormones may be linked to asthma: study

Fluctuations in female sex hormones could play a role in the development of allergies and asthma, according to scientists.
Analysis of studies involving more than 500,000 women highlights a link between asthma symptoms and key life changes such as puberty and menopause.
"Asthma and allergy symptoms are often affected by life events such as puberty and menopause, but the reasons behind this are unclear," said Nicola McCleary from the the University of Edinburgh in the UK.
For the research, published in the Journal of Allergy and Clinical Immunology, the scientists reviewed more than 50 studies of women with asthma from puberty to 75 years of age.

They found that starting periods before turning 11 years old, as well as irregular periods, was associated with a higher rate of asthma.
Onset of menopause - when periods stop and oestrogen and progesterone levels fluctuate - was also associated with a higher chance of having asthma compared with pre menopause.
Many women report that their asthma symptoms change with their menstrual cycle, which may be down to variations in levels of hormones, including oestrogen and progesterone, but the link is unclear.
"Our ultimate goal is to undertake a clinical trial to test the effectiveness of hormonal treatments to reduce symptoms of asthma in women," said Aziz Sheikh from the University of Edinburgh.