Is this part of this bigger study or a separate one?
A new study testing women's ability to react and foresee "challenges what women and perhaps society more generally, assume about their abilities" when they are on their periods - and it is surprisingly positive.
https://news.sky.com/story/women-perform-better-and-make-fewer-mistakes-when-on-their-period-new-research-says-13147714
So employers could turn round and say no to menstrual leave as they need women operating at the best to be at work!