It is probably the last conversation you want to have with your teen, but it is also the most important.

Sex. If you don’t talk to your teen about it, I can assure you, someone else will — a friend or classmate or a friend’s older sibling.

Oftentimes the hallway conversations about sex are not informed and mature discussions. Instead, teens perpetuate myths about safe sex, peer-pressure their friends into doing it, or tell lies about their own experiences.

None of this will help your teen make wise and informed decisions about her body. This is why you need to talk to your teenage son or daughter about sex before someone else does.

You may feel out of control in this area with your teen, but you’re not. A survey cited by the CDC reported that teens said their parents have the greatest influence over them when it comes to the decisions they make about sex. That’s right — greater than their friends, siblings, or even the media.

You have much more influence than you realize. Sit down with your teen and talk to him or her about sex, the human body, and the choices your child makes. If you’re not sure what to say, here are three things you should be talking to your teen about now, before it’s too late.

1.) Birth control is not disease control. When birth control pills arrived in the 1960s, my generation felt we had just what we needed to take ultimate charge of our sexual lives. But what we failed to see was the curse that accompanied it. The pill helped us to stay focused on only one consequence of sex: pregnancy. What we didn’t see in the meantime were the growing numbers of sexually transmitted diseases.

By telling our kids that contraception equals “safe sex,” we perpetuate a dangerous lie. Birth control is not disease control.

Consider these statistics:

  • We now have 35 known sexually transmitted diseases (STDs). In 1960, we only had two.
  • Teenagers make up one-third of the U.S. population, but they carry 50 percent of STDs.
  • One in four teens has an STD.

Don’t simply warn your teen about getting pregnant, or getting someone else pregnant.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

Make sure your teen knows the facts about STDs and that birth control is not the solution to safe sex.

Related: Three Secrets of Raising Emotionally Healthy Children

2.) Beware the “emotional STD.” As STD rates have soared, so have depression rates in teens. In 2015, an estimated 3 million adolescents age 12 to 17 in the U.S. had at least one major depressive episode in the past year. From 1999 to 2014, the suicide rate in girls age 10 to 14 tripled. About 20 percent of teens will experience depression before they reach adulthood.

This is no coincidence. Sex is a major event for any person, but a teen does not have the emotional tools to deal with such an event. This is why I see so many sexually active teens battling depression.

Make sure your teen knows that sex is not just a physical act. It always involves the emotions and the soul. It is mental as well as physical. Trust me, nobody is telling them this at school. It’s not “cool” to talk about emotions and sex. Your teen needs you, her parent, to tell her the truth.

Related: Kids Don’t Want Perfect Dads — They Want This

3.) You’re a safe place. Even more important than presenting the facts and the dangers of sex to your teen is to make sure your child knows he can come to you with any questions, concerns or fears. Make sure he knows you are a safe place for these conversations. Connect with him on an emotional level and emphasize he can trust you. You want to be your teen’s first stop, not last resort, when it comes to questions about sex.

These are the years your child needs you the most.

I know the teen years are tough. Emotions are high, your teen feels distant, and you’re confused by his behavior. But parents, these are the years your child needs you the most. If you remain connected with him and have the tough, difficult and awkward conversations that you both want to avoid now, he will feel equipped and supported to make good and wise decisions about sex in the future.

Dr. Meg Meeker has practiced pediatrics and adolescent medicine for more than 30 years. She is the author of the book “Hero: Being the Strong Father Your Children Need” (Regnery Publishing, May 2017), along with a number of digital parenting resources and online courses, including The 12 Principles of Raising Great Kids.