Teen births, meanwhile, have plummeted about 57 percent over the last 30 years.
Researchers surveyed roughly 2,000 boys and girls, 15 to 19. (They also interviewed about 1,770 young adults, 20 to 24, about their high school encounters.)
The share of teen girls who reported they've had sex at least once dropped from 51 percent in 1988 to 44 percent in 2013, they found. Abstinence was more pronounced among the guys: 60 percent of teen boys in 1988 said they’d had sex, compared to 47 percent in 2013. Much of the decline for both boys and girls occurred between 1988 and the period of 2006-2010, and numbers have held steady since then.
Crotchety adults may joke: Maybe they’re too busy messing with their iPhones.
That’s actually a decent theory, said Dr. Brooke Bokor, an Adolescent Medicine Specialist at the Children's National Health System. More teenagers than ever have smartphones, including those with no traditional computers at home. Many are more comfortable searching in private for credible information about sexual health, she said. They could be better educated about the risks -- and more mentally prepared before that first heated moment ever comes.
“They’re looking on the web,” Bokor said. “They’re looking for guidance from parents, guardians and physicians. They can and will make positive decisions for their own health, both sexual and otherwise. We really need to be prepared to treat our youth and young adults as educated consumers.”
One good example, she said: The National Campaign to Prevent Teen and Unplanned Pregnancy, a private non-profit organization runs Bedsider.org. This week’s featured articles include “Not awkward: 5 tips for talking to anyone about sex” and “<3 your birth control.”
Another possible driver of the sexual slowdown is the growing popularity of the HPV vaccine, which is now widely offered to boys and girls as young as 11. The shots, of course, come with an educational conversation. Kids learn earlier about the prevalence of STIs and how they're spread.
(Contrary to some parents' worries, research shows the advent of Gardisil did not spark an upswing of sexual recklessness among tweens.)
"They learn from doctors that you can catch HPV even if you use a condom," Bokor said, emphasizing some common conditions spread through skin-to-skin contact. "They might think: How else can I stay healthy?"
The majority of kids these days use some form of contraception, the CDC data shows. The use of emergency contraception -- like the Plan B pill -- for teen girls grew from 8 percent in 2002 to 22 percent in 2013.
But teenagers still aren’t using the most effective forms of contraception: 97 percent of teen girls opt for condoms over birth control pills and the IUD. The withdrawal method also appears to be pretty common:
The survey data also provides a window into when first times are most likely to happen:
Girls who reported using some form of protection during their first sexual encounter were half as likely to become teen moms than those who did not, the CDC reported.
That suggests birth control has played a key role in curbing teen parenthood. Births to girls 15 to 19 plunged from 84 per 1,000 teens in 1991 t0 26 in 2013.