If you’ve been putting off having “the talk” with your son or daughter, don’t delay another day.

A new study published in the journal of the American Academy of Pediatrics indicates that by the time parents broach the subject of sexuality, nearly half of children have already passed key sexual milestones.

In a series of surveys with 141 parents and their teenage children, researchers found more than 40 percent of teens had sexual intercourse before any discussion with their parents about sexually transmitted disease symptoms, condom use, choosing birth control, refusing sex or what to do if a partner refuses a condom.

“This is important because pattern and behaviors within relationships are established early,” said researcher Megan Beckett. “If parents hope to have the most effect on their teens’ sexual development they should convey their attitudes, values, and (accurate) knowledge before these patterns are set (before first intercourse).”

Researchers suggest pediatricians encourage parents to have more timely communication with their children about important sex-related topics. They could also provide suggestions for specific topics that should be covered and advice on how to discuss them with parents who don’t know what to say. Pediatricians also can address these issues in one-on-one conversations with adolescents in their office.

“Don’t wait and give the ‘big talk,’” says Beckett. “Start early and repeat, repeat, repeat. All parents know that their children and teens don’t necessarily ‘hear’ or understand them the first time. Starting early and repeating talks also makes these discussions more comfortable for both the parent and the child over time.”

And if your child isn’t asking any questions?

“Then parents might want to take advantage of teachable moments that occur in television shows, with music lyrics, newspaper reports or problems friends face,” she suggests.