Hello, and I hope I can help you today.
Bleeding after sex can occur in women of all ages, but it is not unusual at all when a girl is in her teen years because her own menstrual cycle is still maturing and also chafing inside from sex can occur. Furthermore, any bleeding from the
uterus can produce cramps, even if it's at the incorrect time.
Condoms are extremely effective in preventing
pregnancy if they were applied before any genital contact and remain on during intercourse and when you pull out. Furthermore, the most common sign of pregnancy is a missed menstrual period, so if your girlfriend has not actually missed a cycle she really does not need to worry about pregnancy.
If your girlfriend herself is also on birth control pills, irregular bleeding and spotting can be a side effect of the pill as well.
So in summary, there are lots of reasons why your girlfriend could be bleeding irregularly, but if you are using proper
contraception and condoms, pregnancy is not really one of the things you need to be concerned about.
If your girlfriend starts to bleed regularly after sex she really should be evaluated by a doctor, as inflammation or infections of the
cervix can cause postcoital (after sex) bleeding as well.
I hope that I was adequately able to answer your question today, and that my advice was reassuring.
Best wishes, Dr. Brown