• asthma

There has long been interest in whether sex hormones play a role in the development of asthma and influence its natural history, but much of this evidence base is of poor quality and hence difficult to interpret. This interest stems from clinical experiences, and findings from a substantial body of epidemiological investigations, and a smaller body of mechanistic and experimental studies. These have mainly focused on oestrogen and progesterone in females with inconsistent results. The focus on testosterone in both males and females in the linked study by Han et al is therefore welcome but other than these strengths,1 it suffers from many of the same limitations as much of the previous body of epidemiological work. In this editorial, we seek to contextualise the findings from Han et al and offer suggestions on how to strengthen the evidence base for understanding the relationship between sex hormones and asthma.

There is considerable circumstantial evidence implicating sex hormones in asthma. For example, it is widely recognised that asthma is more prevalent in boys in the prepubertal period and that these sex differences reverse after menarche until at least the time of the menopause.2 These sex differences are also seen in asthma admission patterns.3 There is in addition evidence that fluctuations in sex hormones associated with menstruation, pregnancy and menopause can influence some women’s asthma control.4 Furthermore, there …