If you have severe asthma, you rely on inhalers or medicine to open your airways so you can breathe. You’re no stranger to the doctor’s office or, for severe attacks, to the emergency room.
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If you’re a woman, you’re more likely to find yourself in this situation.
Could the sex hormones, which mark our developmental and reproductive years, be the reason?
Dr. Zein’s ongoing research, supported by a National Heart, Lung and Blood Institute grant, shows that lung function suffers when:
- Levels of the female hormone estrogen are higher, which happens after puberty for girls.
- Levels of the male hormone testosterone are lower, which happens before puberty for boys.
“The evidence linking the sex hormones to asthma continues to grow,” he says.
Asthma through the years
Asthma is a curious illness: It jumps back and forth between the sexes over a lifetime.
“Up to age 14, boys are more likely to need office and ER visits, as well as hospitalization, for asthma,” says Dr. Zein.
Once a woman’s estrogen levels start falling after menopause, roles reverse once again — men take the brunt of asthma later in life.
“We have demonstrated for the first time that menopause may actually protect women from severe asthma,” says Dr. Zein.
It’s possible that the severity of men’s asthma increases as their testosterone levels decline, but more research is needed to confirm this, he says.
The power of sex hormones
During the childbearing years, asthma worsens prior to the menstrual period in one of every three women with this lung disorder. The result: significant loss of productivity and increased ER use.
Asthma prevalence is higher in multiple subgroups of women exposed to increased levels of estrogen:
- Women whose periods began earlier in life.
- Women who have had multiple pregnancies.
- Women with hormonal disturbances such as polycystic ovary syndrome.
At a 2018 scientific conference, Dr. Zein also reported on a link between endometriosis, and oral contraceptive use, in women with asthma.
Endometriosis and asthma
“Both asthma and endometriosis are related to an imbalance of the sex hormones — and estrogen, in particular,” notes Dr. Zein.
Reviewing records of more than 3 million 20-to-40-year-olds, his team found that 23.8% of women with endometriosis developed asthma at some point, compared with just 13.2% of other women.
Asthma and oral contraceptives
In a study of asthma and birth control pills (which contain estrogen), Dr. Zein’s team reviewed records of more than 6.5 million 20-to-50-year-olds.
They found that women who took oral contraceptives were more likely than other women to develop asthma, with a lifetime risk of 14.3% versus 8.8%.
“We also think birth control pills may benefit women with premenstrual asthma by cooling down their hormonal peaks. But studies have been conflicting, and this must be looked at more deeply,” he notes.
What does this mean for you?
If you’re a woman with asthma, should you stop taking birth control pills?
“We don’t want patients to stop taking oral contraceptives,” stresses Dr. Zein. “Most women of childbearing age tolerate them well.”
And oral contraceptives may keep premenstrual asthma symptoms from worsening at the end of your menstrual cycle.
“We’re simply asking patients to be vigilant,” he says. “Tell your doctor if you notice more asthma attacks while on birth control pills, so that you can discuss hormone-based contraception.”
Because HRT contains estrogen, Dr. Zein says it may temporarily worsen your asthma. “However, we’re not saying, ‘Don’t use HRT’; again, talk to your doctor,” he advises.
“Hopefully, randomized, controlled trials will lead to better recommendations.”
“Everything we’ve looked at suggests the sex hormones affect asthma,” says Dr. Zein. “But how they affect the lungs is still poorly understood.”
One theory is that sex hormones may affect the pace with which hair-like cilia clear mucus from the airways.
“Until the exact mechanism is identified, our research suggests that doctors should consider factors that impact the sex hormones when treating women for asthma,” he says.