By Amy Norton
The study of more than 83,000 women with asthma found that those who used birth control pills for at least three years tended to have fewer severe flare-ups.
The difference between pill users and non-users was small, and the findings do not prove a cause-and-effect relationship, the researchers stressed.
However, there’s reason to believe birth control pills could affect asthma symptoms, according to study author Bright Nwaru.
For one, it’s known that some women with asthma see their symptoms flare at certain points in the menstrual cycle. Fluctuating hormone levels are suspected to be the reason, explained Nwaru, of the University of Gothenburg in Sweden.
“Anecdotal evidence suggests that some women with menstrual-related asthma appear to get relief by taking hormonal contraceptives,” he said.
But, Nwaru added, studies on the question have come to conflicting results.
This latest study, published online Nov. 23 in the journal Thorax, is the “most robust” to date, according to Nwaru. It followed a large group of women over 17 years and found what could be a “small” protective effect of birth control pills, he said.
No one, however, is suggesting women try the pill to manage asthma.
“This is just a link — so it’s not enough [evidence] to use the pill as a treatment,” said Dr. Purvi Parikh, a national spokeswoman for the Allergy and Asthma Network.
According to Parikh, there are various lines of evidence that the body’s sex hormones (like estrogen) affect asthma: Before puberty, boys are more likely to develop asthma than girls are, but after puberty, the reverse is true. Boys also outgrow asthma more often, which all results in asthma being more common in women than men.
Pregnancy plays a role, too. One-third of pregnant women with asthma see their symptoms improve, while just as many have a worsening, said Parikh, who is also a clinical assistant professor at NYU Grossman School of Medicine in New York City.