The proportion of sexually experienced U.S. high school students fell by 13 percent from 1991 to 2005, according to a new federal study that examined prevalence of HIV-related risk behaviors of teenagers.
The research by epidemiologists for the U.S. Centers for Disease Control and Prevention found that the share of teens who acknowledged ever having had sexual intercourse dropped from 54.1 percent to 46.8 percent during that nearly 15-year period.
Among students who said they were sexually active, the study showed a 24 percent drop in the proportion of those who said they had experienced four or more sex partners during their lifetime and a 9 percent decline among those who said they were currently sexually active.
What's more, the percentage who said they had used a condom during their most recent sexual contact grew from 46.2 percent in 1991 to 62.8 percent last year, a 36 percent increase.
Students of both sexes in all grade levels showed a "significant" decrease in risky sex, the federal researchers said.
"The overall decrease in HIV-related sexual risk behaviors among high school students discussed in this report corresponds to a similar decrease in gonorrhea, pregnancy and birth rates among adolescents," Nancy Brener of the CDC's Division of Adolescent and School Health and other authors wrote.
The percentage of sexually experienced black teens fell from 81.4 percent in 1991 to 60.8 percent in 2001. But it has "leveled off" since then, the authors said, and was 67.6 percent in 2005.
"Efforts need to be intensified among black students, who are more likely than white and Hispanic students to report HIV-related sexual risk behaviors," the CDC said in a press release on the report. For example, in 2005, 28.2 percent of black teens said they had experienced four or more sex partners during their lives. For white teens, that proportion was 11.4 percent; and for Hispanics, 15.9 percent.
The report's authors say there must be additional measures aimed at Hispanic students, who "have not experienced [statistically significant] decreases in the prevalence of sexual experience, having had multiple sex partners, or current sexual activity" during the period analyzed. The authors defined the latter as having had sexual intercourse in the previous three months.
The findings are published in today's issue of the CDC's Morbidity & Mortality Weekly Report. Data were derived from eight national Youth Risk Behavior Surveys (YRBS) conducted by the CDC.
The data used were representative of public and private school students in grades 9 to 12 in all 50 states and the District of Columbia. Sample sizes ranged from nearly 11,000 to more than 16,200. Overall response rates for the surveys ranged from 60 percent to 70 percent, the authors said.
They concluded these improvements in health outcome for secondary school students "likely resulted from the combined contributions of parents and families, schools, youth-serving community organizations, health-care providers, the media, government agencies, and the youth themselves," plus the availability of better educational interventions.