# Sex-Based Differences in Bronchial Asthma: What Are the Mechanisms behind Them?
## 4 Sex-Based Differences in Different Life Periods
### Adulthood  
In adulthood, the higher prevalence of asthma in women in comparison to men continues, and the course of the disease in women is more severe and associated with three times more frequent admissions to hospital with asthma complications [84; 85]. This sex-related difference remains until menopause [76; 77; 86; 87].  
Worsening scores in the pulmonary function tests, more frequent asthmatic symptoms, and higher requirements for medication are observed in about one third of women before and during menstruation [88; 89; 90]. [PERSON] et al. [91] found that, in women with asthma, the morning values for peak flows and asthma symptoms deteriorated from the follicular to the luteal phase of the menstruation cycle. These findings were confirmed by other authors, who found the best airflow values at the end of the luteal phase through to the beginning of menstruation, followed by a decline over the subsequent two weeks [92]. However, in healthy controls, no changes in airway functions were observed in relation to fluctuations in estrogen and progesterone during the menstruation cycle [91; 92], suggesting more complex mechanisms may be responsible for perimenstrual worsening of asthma status in women [76]. In this context, the recent finding by [PERSON] et al. [93] that 24% of women with AERD also show perimenstrual worsening of asthma could be interesting.  
Several studies have investigated the effects of contraceptive pill use in premenopausal women on the changes in lung functions and the occurrence of asthma symptoms. However, the results of these studies were often contradictory. While [PERSON] et al. [94] demonstrated that normal and overweight women taking hormonal oral contraceptives reported higher occurrences of wheezing and other asthma symptoms in comparison to lean women, other authors found no differences in lung functions or asthma medication use in women taking contraceptives compared to those with a natural menstrual cycle [95] or even found decreased airway responsiveness in women taking contraceptives [96]. This discrepancy indicates that further studies should be performed to evaluate the effects of contraceptives containing gestagen only or combined hormones (gestagen + estrogen) with different doses or ratios of gestagen and estrogen in relation to current asthma status, as well as new onsets of asthma.  
Asthma control may change during pregnancy. In an older study by [PERSON] et al. [97], asthma symptoms increased in about one third of pregnant women while the status reverted within the first three months _post-partum_ in about 73% of them. However, other studies found no change or even improvements in asthma symptoms [98; 99]. A more recent analysis by [PERSON] et al. showed that asthma exacerbations during pregnancy occurred in 12.6% of patients with asthma initially classified as mild, 25.7% of patients with asthma initially classified as moderate, and 51.9% of patients with asthma initially classified as severe, while in 30% of mild asthma patients, the course of the disease worsened to moderate and, vice versa, 23% of patients with moderate-severe asthma showed improvements in their status to mild asthma [100].  
The contradictory results of the studies performed with women undergoing menopause may be attributable to fluctuating levels of hormones, the use of hormone replacementtherapy (HRT), and the influence of other factors, such as smoking or concomitant diseases [101; 102; 103; 104; 105; 106; 107].  
Nevertheless, similarly to the puberty period, a clear relation between asthma prevalence and obesity can be observed in women but not in men, and a higher risk of asthma was reported in obese women than in women with normal body weight [108; 109]. Late-onset asthma in obese women, which represents a special phenotype of asthma, is characterized by more severe symptoms, increased counts of neutrophils in sputum, and higher requirements for treatment [110; 111].