So says a recent article in Nature. So, ladies, if you want to impress a guy, wait till you're ovulating, I guess.
What I found most intriguing in this article, however, was the last paragraph, which talks about earlier studies:
Earlier studies have indicated that men might use other clues, such as female body odour, to help them pinpoint their partner's fertility. Others have shown that a woman's ears and breasts actually become more symmetrical in the days leading up to ovulation.
Women's ears become more symmetrical. How does that even work? The world is filled with wonders.