The reason that peeing after sex can’t prevent pregnancy comes down to anatomy. The urethra, the hole where urine exits the body, is separate from the vagina, the hole where the penis enters the woman’s body during penile-vaginal intercourse. Since the sperm is ejaculated into the vagina, peeing won’t remove it.
Related to this, you might think that cleaning out the vagina using vinegar, vaginal steaming, douches, or yogurt would be more effective since they do enter the vagina. However, according to KidsHealth, these won’t prevent pregnancy either. Sperm swim too fast and are probably already well on their way to the egg before you’ve even begun. Also, douching can actually push the sperm even further in and you may even get a pelvic infection in the process.
