Men can come to know when their partners are having their periods just by listening to their voice; a new study reveals.

The women were recorded counting one to five four different times over a period of one full menstrual cycle.
The men were made to listen to all the recordings and were asked to identify which recordings were made during a woman’s periods. The researchers found that men managed to identify the correct tape 35 percent of the time.
The study is published in the journal Ethology.
Source-Medindia