It is normal for some women to bleed the first time they have vaginal intercourse but at the same time some women don’t bleed at all, and that’s normal too. The bleeding is caused from the hymen stretching and usually it is just a small amount of bright red blood. Some women are born with extra hymenal tissue that covers more of the vaginal opening so penetration can be painful and there tends to be more bleeding. It’s possible that you started your period while you were having sex but that doesn’t explain the pain you had. We recommend that you make an appointment with your health care provider (HCP) to find out if you might have a small opening with extra hymenal tissue. It’s best if you don’t try to have sex again until you get checked by your HCP.