A recent study has revealed that progesterone, a component found in most of the hormone-based birth control is useful in stopping the worst affects of influenza flu in women.
In addition to it, the hormone also helps the damaged lung cells to heal more quickly, reports the Mirror.
The findings suggest that sex hormones have an effect far beyond the reproductive system and that progesterone could prove be a viable flu treatment for women.
The World Health Organisation (WHO) has reported that more than 100 million young adult women around the world are on progesterone-based contraception.
And women of reproductive age are twice as likely as men to suffer from complications related to the flu virus.
Lead researcher Sabra Klein said, "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."
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Adding, "Understanding the role that progesterone appears to play in repairing lung cells could really be important for women's health. When women go on birth control, they don't generally think about the health implications beyond stopping ovulation and it's important to consider them."
WHO has already listed hormonal contraceptives as an essential medication because of the profound benefits these compounds can have on women's health by widening the interval between pregnancies, including decreased rates of maternal mortality and improved outcomes for babies and children.
For their research, Klein and her colleagues placed progesterone implants in female mice and left other mice, also female, without.
The mice were then infected with influenza A virus.
Both sets of mice became ill, but those which had the implants had less pulmonary inflammation, better lung function and saw the damage to their lung cells repaired more quickly.
The researchers found that progesterone was protective against the more serious effects of the flu by increasing the production of a protein called amphiregulin by the cells lining the lungs.
When the researchers bred mice that were depleted of amphiregulin, the protective effects of progesterone disappeared as well.
Klein also stated that progesterone lessened the inflammation and damage associated with the flu.
When female mice and possibly humans get sick with the flu, their natural levels of progesterone fall.
Women on hormonal contraceptives, be it a birth control pill, IUD or injection, get a steadier level of progesterone which overrides what the ovaries make naturally or what the virus takes away during infection.
Klein said, however, there is no scientific data to date showing whether progesterone in humans has any relationship to flu severity since no researchers have asked those questions.
She added researchers, who are conducting flu surveillance, have added questions about specific forms of birth control to their questionnaires so they learn more about the potentially protective effect of progesterone in humans.
The mice in the original study were given actual progesterone and not a synthetic form of the hormone, which is what is in contraception.
More recently, as part of their ongoing research, Klein gave synthetic progesterone to mice and found a similar effect.
Now the researchers are studying the precise mechanism for how progesterone increases the concentration of amphiregulin in the lungs.
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."
The findings were published in the journal PLOS Pathogens.