According to the Centers for Disease Control, only certain fluids from an HIV-infected person can transmit HIV. The bodily fluids containing the highest concentrations of the virus include: blood, semen, vaginal fluid, breast milk and other fluids containing blood.
Vaginal sex and anal sex are the most common ways that HIV is transmitted. Fluids produced by the vagina to keep itself clean and to help make intercourse easier also contain HIV, if she is infected.
If a woman with HIV has sexual intercourse with a man who does not wear a condom, HIV could get into the man's body through broken skin on his penis, by getting into his urethra (the tube that runs down the penis) or through the inside of his foreskin (if applicable). Any contact with blood during sex increases the chance of infection, rendering intercourse during a woman's period more risky.