HIV is spread through the blood, pre-seminal fluids, semen, vaginal fluids, rectal fluids, or breast milk of a person who has HIV. In the United States, the main risk factors for HIV transmission are the following: Having anal or vaginal sex with a person who has HIV without using a condom or taking medicines to prevent or treat HIV
Sharing injection drug equipment (works), such as needles, with a person who has HIV. Several factors can increase the risk of HIV in women. For example, during vaginal or anal sex, a woman has a greater risk for getting HIV because, in general, receptive sex is riskier than insertive sex. Age-related thinning and dryness of the vagina may also increase the risk of HIV in older women. A woman's risk of HIV can also increase if her partner engages in high-risk behaviors, such as injection drug use or having sex with other partners without using condoms.
Some HIV medicines may reduce the effectiveness of hormonal contraceptives, such as birth control pills, patches, rings, or implants. Women taking certain HIV medicines may have to use an additional or different form of birth control. For more information, view the AIDSinfo HIV and Birth Control infographic.