Girls did not bleed for the first time, two aspects of the possibility: First, the hymen hole is relatively large, elasticity is good, although the occurrence of sexual intercourse, the hymen did not rupture bleeding, rupture bleeding will occur only at the time of delivery. Secondly, the hymen may have been ruptured before, such as having had sex, or usually participate in strenuous sports suffered a riding injury, which at that time led to the hymen rupture bleeding and pain, if carefully recalled, it should come to mind. If you are not sure, you can also see a doctor to check whether the hymen has ruptured or not, it is easy to see. It is also possible that the hymen is relatively thin, although there is pain and bleeding during sex, but due to the amount of very small, not careful attention, if you can not see.