What you've heard: Once they’re in your body, sperm literally have to swim upstream to make their way to a waiting egg. Some women try to make the trip easier by doing a headstand or raising their feet in the air.
Does it work? Gravity does help sperm get where they need to go. But post-lovemaking gymnastics are unnecessary. “When a man ejaculates it’s at such incredibly high velocity that the semen has to hit the cervix. You don’t have to stand on your head—sperm swim,” says Alice D. Domar, Ph.D., director of the Domar Center for Mind/Body Health and assistant professor of obstetrics and gynecology at Harvard Medical School.
“However,” says reproductive endocrinologist Steven Bayer, M.D. of Boston IVF, “it is reasonable to lay supine for five minutes after ejaculation has occurred. When you get up it is normal for some of the ejaculate to come out.”