Teens Are Having Less Sex – and Are Being More Careful When They Do

New research from the Centers for Disease Control and Prevention's National Center for Health Statistics found that 55 percent of teens who've had sex prior to age 18 are protecting themselves; the usual method of protection was a condom. The 2011 to 2015 CDC study, published Thursday, gathered data from more than 4,000 teenagers.

The study also showed that teens are having less sex than they used to. Just 42 percent of female teens said they had sex at least once, compared to 51 percent in 1988. That number fell more significantly for men, from 60 percent in 1988 to 44 percent, according to the study.

For the purposes of the study, researchers defined sex as vaginal intercourse between male and female 15 to 19-year-old teens.

Pregnancy concerns play a key factor in contraceptive use. Rates have declined for teen pregnancy since a peak in the 1990s, study author Joyce C. Abma of the National Center for Health Statistics told Reuters. Until 2002, teen sexual activity was falling fast, though there has been a more measured drop since as contraceptive use has grown.

"Whether and to what degree teenagers want to avoid pregnancy influences their sexual and contraceptive behavior," write the study authors. "Furthermore, the majority of female teenagers (88.5%) reported that they would be a little or very upset if they became pregnant, and having these feelings was associated with a higher likelihood of contraceptive use," they added.

Though the contraception data may be encouraging, that doesn't mean this issue is resolved.

The U.S. teen pregnancy rate is high compared to most developed countries, Abma told CBS News. "That in addition to sexually transmitted infections, these are public health issues that we need to get a hold on what the causes are. Sexual activity and contraceptive use are the direct mechanisms that drive these trends."

As for who they're having sex with for the first time – 74 percent of females and 51 percent of males said it was who they were "going steady" with. But for 20 percent of females and close to 40 percent of males, Reuters notes, they claim to have had sex for the first time with someone who was just a friend or someone they were "going out (with) every once in a while."