- Researchers say women who take contraceptives such as birth control pills have a lower risk of developing asthma.
- They say it’s because these contraceptives reduce the production of certain hormones that have been linked to asthma.
- This phenomenon may explain why the rate of asthma increases in females after they reach the age of puberty.
Hormonal contraceptives such as birth control pills may reduce the risk of asthma in women of reproductive age.
That’s according to a new study of more than a half million women.
Researchers concluded that study participants who used hormonal contraception in either pills, patches, or shots had a lower risk of developing asthma than their peers who didn’t take hormonal contraceptives.
In childhood, asthma is more common in boys than girls, but from puberty onward the risk of developing asthma and having more severe symptoms is higher for women than men.
Researchers say it’s possible that female sex hormones are responsible for this phenomenon.
“This male to female switch in asthma incidence was observed in an important study (The Childhood Asthma Management Program),” Dr. Richard George Barbers, a professor of clinical medicine at Keck School of Medicine of USC in California, told Healthline.
“The study showed that as puberty scores increased in boys, asthma symptom scores began to decrease at about age 14,” he said. “Whereas as puberty scores increased in girls, asthma symptom scores also began to increase at approximately 10 years old.”
“Why the switch at puberty? A logical connection, but not clearly established, is that sex hormones are important in asthma pathogenesis,” Barbers said.
According to the study authors, every event related to hormones in the female reproductive life cycle (onset of period, menstruation, pregnancy, and menopause) is associated with variance in clinical outcomes of asthma.
“In some women, asthma symptoms worsen during menstruation, perhaps because of fluctuations in estradiol and progesterone levels,” the study authors wrote.
“Hormonal contraceptives suppress the production of endogenous sex hormones and may… contribute to improve asthma outcomes,” they added.
In undertaking the study, the researchers followed more than 500,000 British women, ages 16 to 45, between 2000 and 2016.
During that time period, slightly more than 25,000 of the women developed asthma.
The researchers adjusted the data to account for factors such as obesity and smoking.
They still found that those who used hormonal contraceptives had a 30 percent lower risk of developing asthma than women who didn’t use contraceptives.
Dr. Purvi Parikh, an allergist and immunologist in New York City, as well as a national spokesperson for the Allergy and Asthma Network, said the findings of the study are not surprising.
“It is well known [that] hormonal changes have large impacts on mast [allergy] cells. For example, allergic reactions and asthma attacks are worse during menstrual cycles and girls are more likely to have asthma after puberty than before,” Parikh told Healthline.
“Estrogen has effects on mast cells, which are the immune cells responsible for allergies and asthma. That is why we see increases after puberty, with menstruation, and sometimes in pregnancy,” she added.
In the new study, researchers also reported that the benefits against asthma risk were higher for women who were on hormonal contraceptives for a longer period of time.
Barbers said that gender disparities in asthma is a major issue that warrants further investigation.
“I do not think we understand enough about the role of estrogen in asthma. Although this is an observation many have considered in past decades, I think we are at the frontier to better understanding the impact of hormones on asthma,” he said.
Currently, asthma treatments don’t involve hormone-based therapies. Treatment options vary based on asthma severity.
“Commonly, inhaled corticosteroids combined with other medications such as inhaled bronchodilators are used,” Parikh said. “For more severe asthma we may add an injectable medication such as a biologic which targets areas of the immune system that cause asthma. None of these medications are impacted significantly by hormones.”
Barbers said there’s still much to learn about the relationship between female hormones and asthma.
But it’s likely just one of many factors that can influence asthma onset and severity.
“I believe we have to be cautious about oversimplifying our current understanding of asthma,” he said. “Asthma is an extremely heterogeneous condition that has complex associations and influences. Finding a single mechanistic thread about what causes or worsens control of asthma would ignore the many diverse cohort populations affected with asthma.”
The researchers of the study argue that the relationship between hormonal contraceptives and asthma should be further investigated in a clinical trial to see if the same results are achieved in a controlled setting.
But they say their current findings do not warrant changes in management guidelines for asthma.
Experts say although one day it may be possible that hormonal therapies could be used in the treatment of asthma, more evidence is needed to support this.
“It is possible if the evidence is clear and supportive. However, we will have to balance this with the risk of the adverse events that are associated with such hormonal therapy, most significant would be the occurrence of thrombotic events,” Barbers said.
Parikh argued that current treatment options for asthma are much safer than hormonal contraceptives.
“Hormonal treatments aren’t without side effects and risks such as blood clots, weight gain, and mood disturbances. Current asthma controller medications are far safer with less side effects than hormonal contraceptives,” she said.