We can finally destroy the myth that having a period makes you less competent

For way too long, people have played menstruation for laughs. These hilarious jokes usually come back to a familiar punch line: Women just can't function when they bleed.

It's not just a joke, either. That trope has been used by men and women alike to justify why we can't have nice things, including a female president.

But a new study published Tuesday in Frontiers in Behavioral Neuroscience offers some quality research to destroy the myth of the woman turned incompetent by her period.

The study took dozens of women and tested their cognitive abilities several times over the course of two consecutive menstrual cycles. The researchers found no consistent associations between fluctuations to the women's hormones and their cognition.

"I think this research shows very clearly that women function very well despite having hormonal changes," says Brigitte Leeners, the study's lead author and a professor in the Clinic for Reproductive Endocrinology at the University Hospital Zurich. "You cannot use hormonal changes as an excuse that there would be limitations in their performance."

Someone might want to alert Donald Trump, given his interest in women and how they bleed. Last year, he quipped that former Fox News anchor Megyn Kelly got upset while moderating a presidential debate and had "blood coming out of her wherever." He denied the comment referenced her period, but it was hard not to see the connection.

Though previous research has suggested that estrogen and progesterone, both female sex hormones, may affect a woman's cognitive functioning, Leeners says past studies had significant limitations and methodological biases. For instance, none of them measured hormonal levels and cognition over the course of two periods, which would help establish a causal relationship between hormones and ability.

Leeners' team actually did initially see decreases in cognition during the first menstrual cycle. But when they performed the same tests for attention span, working memory, and cognitive bias during the second round, those effects disappeared. She believes the initial observation could've captured false positives caused by random variation. The difference between the first and second cycles could also reflect something called "practice effects." Basically, the women may have know the tasks from before and got better at answering correctly.

The researchers also compared the participants' performance to one another as well as analyzing it over time for each person, and they found no difference.

Via Giphy

Not testing women for consecutive periods may seem like a glaring oversight, but Leeners says there's a practical reason for it.

"If other research teams have limited resources, you’re quite tempted to do one cycle," she says. "And if you discover something significant, this is always nice to publish."

Participants in Leeners' study were paid 500 Euros each for extensive hormone measurements and comprehensive cognitive testing four times during each menstrual cycle. Sixty-eight women completed both the first and second rounds, and it's easy to see how the experiment would quickly get costly in both paying the subjects and researchers. Prior studies used much smaller sample sizes — some had fewer than 10 participants.

Leeners wants to see more rigorous studies on this subject, but her findings do line up with recent research showing the associations between hormone levels and cognition don't exist or are inconsistent. Plenty of women the world over could have told you that, but sometimes it takes science to help destroy a myth as powerful as this one.