Your question would have to be taken within a certain frame of reference. For instance, it is important for you to specify whether you are talking about having had intercourse for the first time. In women, there is a tissue called the hymen, which blocks the entrance of the vagina. This is something that is present in all women naturally. During the first sexual act for a woman, or when a woman loses her virginity, this tissue ruptures due to the insertion of a foreign object in an area where no such thing has occurred before. Sometimes, some women bleed at the rupturing or tearing of the hymen. While this may cause some discomfort and mild pain to a woman, it is rarely a cause for concern after the first time she has sex. It is also important for you to know that the bleeding would be slight, perhaps restricted to a few drops. It is not as if this will make a lady bleed copiously.
It is important for you to know that it is not always that the hymen ruptures and bleeds. There are certain activities that are known to damage or rupture the hymen other than having sex. These would commonly include horse riding or excessive cycling or swimming as well as wearing tampons during the menstrual period. As believed in certain ancient cultures, bleeding during intercourse is not considered a sign of virginity anymore, and it must also not be taken as such. It is also good to know that if appropriate care is taken to make the woman feel comfortable and there is appropriate sexual stimulation, then she will not be in any kind of pain, and in all possibility may not even bleed. A certain amount of gentleness is called for to make her feel comfortable, and preferably, it should be exercised.
answered by M W