Dr. Farah Kroman:  Having sex is an important decision. Make sure you are really ready and have protection - from sexually transmitted diseases and from unwanted pregnancies. There can be a little pain the first time you have sex. Ask your partner to go slow, be gentle and don't force anything. Bleeding the first time you have intercourse can be quite common, particularly if nothing has been inserted into the vagina before (for example, a tampon). Bleeding on first intercourse is usually caused by the hymen breaking. The hymen is a thin membrane, which partially covers your vaginal opening, almost every girl is born with one. If you do bleed after intercourse, it should only be a small amount (for example spotting for a few hours).