At least one in four U.S. teen girls has a sexually transmitted disease, according to a recent national study by the Centers for Disease Control and Prevention.

The news is shocking. What does it mean for parents? Evidently, somewhere along the line we’re failing. After all, we’re our children’s first teachers. Either our message on abstinence isn’t getting through, or our talk on safe sex is failing on deaf ears. Or perhaps, we never had the talk.

Released earlier this month, the study of girls ages 14 to 19 found that the most common sexually transmitted disease is a virus that can cause cervical cancer and the second most common can cause infertility.

In this case, lack of knowledge or poor information can be deadly. It’s obvious that sex isn’t a topic that we can continue to ignore – as difficult as it is to discuss with our teens. And sex is apparently equally difficult for teens to bring up with adults. Consider that only about half of the girls in the study acknowledged having sex. While some teens define sex as only intercourse, other types of intimate behavior, including oral sex, can spread some infections, a fact that teens need to know.

It’s no longer enough to say, “Don’t have sex.” Evidently, it’s not working. “Just say no,” always needs to be followed up with concrete information. We have no problem telling our kids not to do drugs and warning them about specific dangers, like AIDS from the shared needles of intravenous drug users. Why not do the same for sex? Have the whole talk: Sex can mean an unexpected arrival – in the form of a child or a disease – and here’s how diseases are spread and how they can be avoided. Don’t forget that condoms can help prevent the transmission of some diseases.

No one’s talking about STDs in boys yet because they weren’t in the survey, but can they be far behind? Parents are in the best position to protect their teens. Arm them with accurate information. Tell them how prevalent STDs are. Leave your embarrassment – and theirs – behind so they have a future ahead.