My HormonologyFile this one in the strange-but-true category: When you and your partner are ready to try for a baby, your guy’s testosterone level rises when you’re ovulating, reveals a study in the journal Hormones and Behavior. Researchers theorize it’s to help boost virility, upping your chance of conception. But, if you and he are not trying to have a child, his testosterone level doesn’t experience this fertility-aiding surge! Interesting, right?