Most folks assigned female at birth (AFAB) know to pee after sex to prevent a UTI. If you're trying to get pregnant, however, urinating after sex will not harm your chances. It's important to remember that when you're having baby-making sex, sperm is ejaculated near the cervix. Sperm move quickly, so despite the effects of gravity, they will still reach your uterus and fallopian tube even if you pee after sex. In addition, because of your anatomy, the urethra does not exit near the vaginal canal, so it's highly unlikely that urine or seminal fluid will mix.