You are more likely to spread an untreated STI to others if you do not treat it. Using condoms and practicing safer sex does not eliminate the risk of transmission. Women and men can become infertile if curable STIs like chlamydia and gonorrhea go untreated. Syphilis complications can also cause obstructions in the epididymis, increasing the risk of infertility in men. In addition to dangers to a pregnant woman, many STIs can also pose a threat to an unborn child. You may be unable to carry your baby to term because of an infection, but the infection may also be transmitted to your baby during or before delivery. HIV infection is more likely to occur if you have certain STIs such as herpes and syphilis, which cause open sores. This virus causes open sores which allow the HIV virus to easily enter the body. It is important to treat STIs since it is possible to develop severe and sometimes life-altering complications over time. In some cases, these conditions may progress undetected for years without showing any visible symptoms.