6 reasons for bleeding after sex and how to prevent it, according to OBGYNs Bleeding after sex is common, and is usually due to vaginal dryness, birth control, or rough sex. However, sometimes bleeding after sex may be a sign of an STI or even cervical cancer. To prevent bleeding during and after sex, use lube or see an OBGYN to get tested for STIs. Nothing kills the mood like discovering blood on the sheets after sex. While it may not be the sexiest part of sex, for many, it’s actually quite common. “Bleeding during or after sex that is not related to the menstrual cycle occurs in about 6% to 10% of women,” says Rachel Bowman, MD, an assistant professor in the Department of Women’s Health at The Dell Medical School at the University of Texas in Austin.