12/11/2013 09:59 am ET Updated Feb 10, 2014

Teen Pregnancies Are Declining -- Why Don't Adults Believe That?

Here's the good news: Proportionately fewer teenagers are getting pregnant in this country than at any time since the government started collecting statistics in the 1940s, according to data reported last week.

Now here's the bad news. Adults don't believe it, according to figures released by The National Campaign to Prevent Teen and Unplanned Pregnancy. In a survey conducted by Social Science Research Solutions, an independent research company, nearly half of U.S. adults (49 percent) incorrectly believe the teen pregnancy rate has increased over the past two decades.

As I've learned over years of writing about teenagers, Americans are inclined to think the worst about young people, especially teens (except, perhaps, teens who live under their roofs). Grownups will admit, on occasion, that some dangerous teenage behaviors, such as drunk driving, have declined. But sexual behavior? In particular, unprotected sex? Not a chance.

Federal data rebut their pessimism,showing that since peaking in 1990, pregnancy rates have declined significantly among 15- to 19-year-olds of all racial and ethnic groups and in all 50 states.

Why have teen pregnancies declined? And why do adults deny that possibility?

The biggest reason for the decline has to do with teens themselves, says Bill Albert, spokesman for The National Campaign to Prevent Teen and Unplanned Pregnancy, the organization that released the survey data. "Teens are having less sex and using contraception more often," he says.

Teenagers also have more methods of contraception -- and more effective methods -- than ever before, and a higher proportion use contraception than did teens in the past. Other reasons may include:
* Sex education in school, which has improved in quality and in number of schools offering it, thanks in part to an investment in proven programs by the federal government under President Obama.
* Television shows such as Teen Mom and 16 and Pregnant depict in sobering detail the hardships of real girls having and raising babies. These girls come across as slowly maturing, not irrevocably deficient, young women. That's a change from media portrayals of the past.
* Girls born to teen mothers are more likely than daughters of older mothers to become teen mothers themselves. Thus, as the number of teen mothers decline, the number of babies born to teen moms decline as well.

The skepticism of so many adults is unfortunately, in my experience, not all that surprising. Eleven years ago I wrote about a growing body of scientific evidence showing that teenagers are developing, not deficient, creatures. I reported that when youth were asked to name the values in life that were important to them, a large majority rated highly the very traits adults valued.

I also interviewed at the time a researcher named Susan Bales, whose firm surveyed nationally what adults thought of teenagers. Only one in every six adults said that young people shared adults' ethical values such as honesty and hard work.

What adults think about teenagers matters to teenagers -- a lot. If we continue to expect them to have unprotected sex, chances are good that many of them will. If we deny them the means to prevent pregnancy -- instead of making contraception as cheap and available as possible -- the babies that may result from that will cost not only the teens and their families. It will cost federal, state and local taxpayers as well.

In 2010 alone, the latest year data is available, that cost amounted to $9.4 million, according to an analysis by The National Campaign.