Women tend have a greater risk of contracting an STD/STI simply based on their anatomy. As stated above, in some STDs (i.e. gonorrhea) women are more likely to be asymptomatic which can be dangerous. Symptoms for some diseases (i.e.herpes) may not be as plainly visible for women as well. STDs can also lead to complications for reproduction or can be passed along to offspring. Some STDs/STIs pose as a greater threat to women, for example, HPV has caused cervical cancer in many women while serious health complications in men with HPV has shown to be minimal.
Some women don't even realize that they have a std such as chlamydia or gonorrhea infection and only find out later when they are trying to have children and can't because their fallopian tubes are so scarred from disease