Scientists found that the female sex hormone progesterone “shows promise” in helping women fight the worst effects of the flu. The study, published Thursday in the journal PLOS Pathogens, suggests that progesterone — found in most hormone-based birth control — can help reduce lung inflammation and promotes faster lung repair.

Researchers from the Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, studied two groups of female mice. One group had progesterone implants and the other didn’t. The mice were given actual progesterone and not the synthetic one used in contraceptives. Both groups were infected with the influenza A virus.

The mice that had progesterone implants showed less pulmonary inflammation and better lung function than mice without the implants. Researchers observed faster repair of damaged lung cells in mice with the implants.

They found that the progesterone helped the mice combat the serious effects of the flu by increasing the production of the protein amphiregulin in the cells lining the lungs. Researchers then bred mice that lacked amphiregulin and found that in its absence, the positive effects of progesterone also disappeared. When infected with the flu, the natural level of progesterone in the mice fell. The experiment was repeated by giving mice synthetic progesterone and similar effects were observed.

Scientists believe this may hold good for humans too. Women who take hormone-based birth control have a higher level of progesterone in the body, thus countering the amount lost when down with the flu.

“Despite the staggering number of women who take this kind of birth control, very few studies are out there that evaluate the impact of contraceptives on how the body responds to infections beyond sexually transmitted diseases,” study leader Sabra L. Klein said in a statement. “Understanding the role that progesterone appears to play in repairing lung cells could really be important for women’s health.”

Klein added: “We really want to understand from a therapeutic sense how this could potentially work in humans to keep women from experiencing complications from the flu.”