Just experienced the same thing. Will take a test to see if Iam. I have a friend who is 16 weeks pregnant. She had bleeding after sex. It was pink, the flow was not heavy. She found out from her doctor that it was too rough for her body,and at the time she was only about 2 months pregant. My concern is PCOS or Endometriosis.
A common reason for bleeding after intercourse is a cervical infection or irritation. If that's the case, usually medication or cauterization of the cervix remedies the situation quickly. If it's an isolated situation, it could be just a matter of a small tear during sex due to rougher friction or less lubrication. Bleeding can also indicate more a more serious medical situation, which is why it shouldn't go ignored if it is happening frequently. See a gynecologist for an exam and they will be able to tell you if it's caused by an infection or disease. If its not either of those, just take start to use more lubrication when having intercourse.