In a study conducted at The University of Texas in Austin, female participants were asked to wear pads under their armpits during different stages of their menstrual cycle.
A group of men then sniffed the pads and were asked to rate the attractiveness of the odor.
All of the top rated smells were collected when women were fertile (during ovulation), and all of the least attractive were from when women were menstruating. In fact their testosterone and cortisol levels increased when they smelled the fertile underarm odor.
This means men can actually sniff out the right time to make a baby! How crazy is that?