Blushing: A New Sign of Ovulation?

New research shows that facial redness increases around the most fertile time of the month. But can the blush of ovulation be used to aid couples trying to conceive?

Blushing: A New Sign of Ovulation bikeriderlondon/Shutterstock

Scientists already know that men are more attracted to women's faces when they're ovulating, but the reasons why haven't been clear, until possibly now. A new study published this week in the journal PLOS ONE gives us a new clue: Facial redness in the cheeks increases at ovulation. However, the level of redness is just below what the human eye can notice, so questions remain about whether men, or women themselves, can pick up on it. If so, it might be another way for those trying to conceive to detect their prime fertile time.

Seeing red

For the study, researchers used a special camera to photograph women without makeup every day for at least a month. After running the images through a computer program that measured the color of the same patch of cheek, they compared it to hormone tests and found that the women's faces got redder at ovulation time. "We know from past research that redder skin is more attractive, and that the facial skin of other primate species changes in the same way," study author Dr. Hannah Rowland, a professor in the zoology department of The University of Cambridge in England, tells Fit Pregnancy . "We found that women's faces change in redness over the cycle, but the changes in redness are probably not perceivable by the human eye."

So why does there seem to be a correlation with men finding women's faces attractive around ovulation? "It's still possible that color plays a part," evolutionary psychologist Dr. Robert Burriss from Northumbria University in England, who led the study with Rowland, tells Fit Pregnancy. "We know from past research that women are more attractive when fertile, but if they wear makeup then the effect vanishes. Because makeup changes skin color, this implies that color is important to the cycle effect. But perhaps we didn't look at the right part of the faces. We only examined cheek redness—maybe the redness of the lips changes more."

You're blushing!

Although it may be difficult to use facial redness as a sign to have sex if you're trying to get pregnant, you may be able to notice another clue: that you're actually blushing more. "At the moment, we don't know, but I think it's possible," Burriss says of whether a woman could perceive this blushing increase. There may be other clues you can pick up on as well. "Straight women's pupils dilate more readily at peak fertility, but only when they're shown photographs of their boyfriend. And women are more flirty when fertile, but again only when they are interacting with attractive men. Blushing might work in the same way."

Redness indicates blood flow, which subconsciously makes us think of sex and fertility. That's why women in our society use blush and lipstick, and even wear red, to appear more attractive. But Burriss doesn't think that our natural facial redness evolved to attract mates—it may just be a side effect of hormone fluctuations. "The change in facial redness, though real, probably didn't evolve to signal fertility in the same way that a swollen bum signals fertility in a female chimp," he says. "It looks like the change in redness follows a similar pattern to the change in basal body temperature over the cycle—so it may well be a byproduct. We will have to do more research to confirm that."