So, let’s say your partner tells you that they test “negative” for sexually transmitted infections, and because of that you don’t need to use a condom. You take them at their word and have unprotected sex, right?

Wrong.

Safe sex—a term you’ve probably heard since you were old enough to have sex—means protecting yourself not only from unwanted pregnancy, but from STI’s (sexually transmitted infections), also known as STD’s (sexually transmitted diseases), and especially HPV (some types of which can lead to cancer).

According to the data released in the CDC’s (Centers for Disease Control and Prevention) annual “Sexually Transmitted Disease Surveillance Report,” the number of cases of Chlamydia, Gonorrhea and Syphilis in 2016 was the highest number recorded in this country’s public health history. The more than two million reported cases set an alarming new record, with Chlamydia leading the charge at approximately 1.6 million diagnoses.

For women especially, untreated STI’s can lead to shattering, long-term complications such as infertility, stillbirth and greater vulnerability to HIV infection. Rounding out the remainder of those STI’s reported for 2016 includes HPV, Herpes, HIV, Trichomonasis, Hepatitis, and Zika Virus. HPV, the most common of the STI’s, affected 90 percent of women and 80 percent of men once they became sexually active.

Even if your partner goes to their doctor for an STI check-up and receives a clean bill of health, there is still a chance that you may contract an STI from them. Part of the reason for that is HPV and HSV are difficult to find during a routine checkup unless there is an active wart or lesion on the man’s penis or the woman’s vagina. A partner can transmit both these viruses through sexual contact, even if that partner tested “negative” during a physical exam.

Although regular condom use cannot guarantee 100 percent protection against sexually transmitted infections, it is still the best “safe sex” practice aside from abstinence.