Trends in Sexual Risk Behavior Among High School Students -- United States, 1990, 1991, and 1993

Since the early 1980s, adolescents in the United States have experienced high rates of unintended pregnancies (1) and sexually transmitted diseases (STDs) (2), including HIV infection (3). Since 1990, CDC's Youth Risk Behavior Surveillance System has enabled measurement of priority health-risk behaviors among high school students at the national, state, and local levels (4). This report examines data from the 1990, 1991, and 1993 national Youth Risk Behavior Survey (YRBS) * to describe trends in selected self-reported sexual risk behaviors among U.S. high school students.

The YRBS employed a cross-sectional, three-stage, cluster sample of students in grades 9-12 in public and private schools in all 50 states and the District of Columbia. For 1990, 1991, and 1993, sample sizes were 11,631, 12,272, and 16,296, respectively, and the overall response rates were 64%, 68%, and 70%, respectively. To enable separate analysis of black and Hispanic students, schools with high proportions of these students were oversampled; numbers of students in other racial groups were too small for meaningful analysis. A weighting factor was applied to each student record to adjust for nonresponse and oversampling. Trends were assessed only for sexual risk behaviors measured by questions identically worded in each survey year. To determine temporal differences, 95% confidence intervals were calculated for each estimate by using SUDAAN (5).

From 1990 to 1993, the percentages of high school students remained constant for those who reported ever having had sexual intercourse (i.e., sexually experienced), ever having had sexual intercourse with four or more partners, having had sexual intercourse during the 3 months preceding the survey (i.e., sexually active), having used alcohol or drugs before last sexual intercourse, and having used birth control pills at last sexual intercourse Table_1. In contrast, the percentage of those who reported condom use at last sexual intercourse increased significantly, from 46.2% in 1991 to 52.8% in 1993 Table_1; however, subgroup analyses indicated a significant increase in condom use only among females (from 38.0% to 46.0%) and blacks (from 48.0% to 56.5%) Table_2. Reported by: Div of Adolescent and School Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Editorial Note

Editorial Note: During the 1980s, the proportion of adolescents who reported being sexually experienced increased substantially in the United States (6). The findings in this report indicate that, from 1990 through 1993, the proportion of high school students who reported being sexually experienced remained stable, while an increasing percentage of sexually active students used condoms, thereby reducing their risk for unintended pregnancy and STDs, including HIV infection.

The sex, grade, and race/ethnicity findings in this report may assist in identifying groups with higher prevalences of sexual risk behaviors. However, the underlying causes (e.g., education levels, economic factors, or cultural influences) for within-subgroup differences could not be addressed in this study.

In 1991 and 1992, two health outcomes associated with sexual risk behaviors--live births and gonorrhea--also declined. Live-birth rates among 15-19-year-olds decreased in 40 states and the District of Columbia, increased in eight states, and were stable in two states. In addition, rates of gonorrhea decreased among 15-19-year-old males in 45 states and the District of Columbia and among 15-19-year-old females in 41 states and the District of Columbia. Of the 41 areas reporting declines in live-birth rates, 34 also reported declines in gonorrhea rates for both males and females; six other states reported declines for either males or females. Overall, live-birth rates for adolescents decreased significantly (2%) (7), and gonorrhea rates decreased significantly among both adolescent males and adolescent females (20% and 13%, respectively) (8).

The plateau in the proportion of high school students who reported being sexually experienced, the increasing rates of condom use among high school students, and the decreasing rates of live births and gonorrhea among adolescents may reflect, in part, efforts to reduce risks for HIV infection and other STDs among adolescents. For example, since 1986, CDC has collaborated with local, state, and national health and education agencies, national and community-based organizations, and the media to increase development, implementation, and awareness of HIV-prevention education programs for youth.

Despite the decreases in live-birth rates and gonorrhea rates and the increases in condom use, the findings in this report document that many adolescents continue to be at risk for HIV infection, other STDs, and unintended pregnancy because they engage in unprotected sexual intercourse. Efforts to assist all adolescents in delaying first sexual intercourse and increasing condom use among those who do engage in sexual intercourse must be emphasized by health, education, and social service agencies and providers.

The data presented in this report and other data describing changes in rates of pregnancy, abortion, live birth, and gonorrhea among adolescents during the 1980s and 1990s have been summarized by state and for the nation in a new CDC monograph **, Adolescent Health: State of the Nation -- Pregnancy, Sexually Transmitted Diseases, and Related Risk Behaviors Among U.S. Adolescents (8).

References

1. Ventura SJ, Taffel SM, Mosher WD, Henshaw S. Trends in pregnancies and pregnancy rates, United States, 1980-88. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1992. (Monthly vital statistics report; vol 41, no. 6, suppl).

2. Wasserheit J. Effect of changes in human ecology and behavior on patterns of sexually transmitted diseases, including human immunodeficiency virus infection. Proc Natl Acad Sci U S A 1994;91:2430-5.

3. Lindegren ML, Hanson C, Miller K, Byers RH Jr, Onorato I. Epidemiology of human immunodeficiency virus infection in adolescents, United States. Pediatr Infect Dis J 1994;13:525-35.

4. Kolbe LJ, Kann L, Collins JL. Overview of the Youth Risk Behavior Surveillance System. Public Health Rep 1993;108(suppl 1):2-10.

5. Shah BV, Barnwell BG, Hunt PN, LaVange LM. SUDAAN user's manual, release 5.50. Research Triangle Park, North Carolina: Research Triangle Institute, 1991.

6. CDC. Premarital sexual experience among adolescent women -- United States, 1970-1988. MMWR 1991;39:929-32.

7. NCHS. Advance report of final natality statistics, 1992. Hyattsville, Maryland: US Department of Health and Human Services, Public Health Service, CDC, 1994. (Monthly vital statistics report; vol 43, no. 5, suppl).

8. CDC. Adolescent health: state of the nation -- pregnancy, sexually transmitted diseases, and related risk behaviors among U.S. adolescents. Atlanta: US Department of Health and Human Services, Public Health Service, 1995; DHHS publication no. (CDC)099-4630.

* The YRBS was not conducted in 1992. 

** Single copies of this document are available from CDC's Division of Adolescent and School Health, National Center for Chronic Disease Prevention and Health Promotion, Mailstop K-33, 4770 Buford Highway, NE, Atlanta, GA 30341-3724; telephone (404) 488-5330.

TABLE 1. Percentage of high school students who reported selected sexual risk behaviors,
by year -- Youth Risk Behavior Survey (YRBS), United States, 1990, 1991, and 1993 *
==============================================================================================
                                  1990                   1991                   1993
                           -------------------   -------------------   --------------------
Behavior                     %      (95% CI +)      %       (95% CI)      %       (95% CI)
-------------------------------------------------------------------------------------------
Ever had sexual
  intercourse              54.2  (51.3%-57.1%)   54.1  (51.1%-57.1%)   53.0   (50.3%-55.7%)

Ever had sexual
  intercourse with four
  or more partners         19.0  (17.0%-21.0%)   18.7  (16.8%-20.6%)   18.8   (16.8%-20.8%)

  Had sexual intercourse
    during the 3 months
    preceding the survey   39.4  (36.7%-42.1%)   37.5  (34.8%-40.2%)   37.6   (35.6%-39.6%)

  Used alcohol or drugs
    before last sexual
    intercourse             NA &                 11.8  (10.3%-13.3%)   11.0   (10.2%-11.8%)

  Used birth control pills
    at last sexual
    intercourse            14.6  (12.6%-16.6%)   17.8  (15.6%-20.0%)   18.4   (16.3%-20.5%)

Used condoms at last
    sexual intercourse      NA &                 46.2  (43.1%-49.3%)   52.8   (50.1%-55.5%) @
----------------------------------------------------------------------------------------------
* The YRBS was not conducted in 1992.
+ Confidence interval.
& Data not available; the question was worded differently in 1990.
@ Significantly different at p<0.05. 

TABLE 2. Percentage of high school students who reported condom use at
last sexual intercourse among those who had had sexual intercourse
during the 3 months preceding the survey, by sex, grade, and race/ethnicity
-- Youth Risk Behavior Survey, United States, 1991 and 1993
===========================================================================
                                1991                    1993
Characteristic             %      (95% CI *)        %      (95% CI)

Sex
  Male                   54.6  (51.1%-58.1%)    59.2  (55.4%-63.0%)
  Female                 38.0  (33.8%-42.2%)    46.0  (43.2%-48.8%) +

Grade
   9th                   53.3  (47.3%-59.3%)    61.6  (55.9%-67.3%)
  10th                   46.3  (41.8%-50.8%)    54.7  (50.2%-59.2%)
  11th                   48.7  (42.9%-54.5%)    55.3  (52.3%-58.3%)
  12th                   41.6  (37.9%-45.3%)    46.5  (42.5%-50.2%)

Race/Ethnicity &
  White, non-Hispanic    46.6  (42.2%-51.0%)    52.3  (48.4%-56.2%)
  Black, non-Hispanic    48.0  (44.0%-52.0%)    56.5  (52.5%-60.5%) +
  Hispanic               37.6  (32.1%-43.1%)    46.1  (42.0%-50.2%)

Total                    46.2  (43.1%-49.3%)    52.8  (50.1%-55.5%) +
---------------------------------------------------------------------------
* Confidence interval.
+ Significantly different at p<0.05.
& Numbers of students in other racial groups were too small for meaningful
  analysis.
===========================================================================

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