Last night 03/11/2011, I had sex with my girlfriend without using condom. It was her first sex so she lost virginity during sex and some blood came out.Her period was coming but not sure when is that exactly. At morning 3 am , she had high amount of blood coming out.she told that its her menstruation ,but I am not sure because it may be due to her first sex also. So my question is how can I be sure that she had menstruation? Is there any chance of being pregnant ?

Anytime you have sex, a pregnancy can result. Sometimes it's less likely, but the chance is always there. If you can't afford to have and raise a child, it's better to abstain from sex.

If the bleeding continues for more days and follows the usual pattern of when she has her period, then that is what she has. If she experiences pain and other unusual problems, she should see her doctor.