Teens waiting longer, using better protection

Good news: A shift toward safer, more protective sexual behavior among teens has been confirmed by an analysis of findings from four national surveys.1 This confidence-booster comes on the heels of new statistics from the Hyattsville, MD-based National Center for Health Statistics (NCHS), which show that the birth rate for teen-agers declined 3% between 1998 and 1999 to reach a rate of 49.6 births per 1,000 women ages 15 to 19 — the lowest teen birth rate in the 60 years of recorded data.2

The trends in the 1990s toward later first intercourse and increased condom use are real, conclude researchers who analyzed data from four national surveys:

• National Survey of Family Growth (NSFG), administered by the NCHS to provide comprehensive data on fertility, contraception, marriage, and cohabitation;

• Youth Risk Behavior Surveillance System (YRBS), administered by the Atlanta-based Centers for Disease Control and Prevention (CDC) to help states monitor critical health risk behaviors among teen-agers;

• National Survey of Adolescent Males (NSAM), supported by the Department of Health and Human Services agencies to provide information on the behavior of young men;

• National Longitudinal Study of Adolescent Health, funded by the National Institute of Child Health and Human Development of the National Institutes of Health and other Health and Human Service agencies to provide data on risky behaviors and resiliency factors in adolescents.

Tracking trends, gender differences

Each survey differs in purpose, methodology, and sample, so the researchers focused on a common subset of high school students ages 15 to 17. They examined trends and gender differences in six behaviors:

• ever having had sexual intercourse;

• having had sexual intercourse in the last three months;

• pill use at last intercourse;

• condom use at last intercourse;

• number of partners in the last three months;

• number of lifetime partners.

In both the NSAM and YRBS, researchers found decreases in the proportion of all males and of white males who reported ever having had sexual intercourse and increases in condom use among all males.

A second group of trends reveals a significant finding in one survey with a parallel but insignificant change in another, the researchers state. The YRBS indicates a significant decrease in the proportion of black females who reported ever having had intercourse, with the same finding a suggested trend in the NSFG. A decline in the proportion of Hispanic males reporting ever having had intercourse is significant in the YRBS and insignificant in the NSAM. The decrease in the proportion of white males who reported having had four or more lifetime sexual partners is significant in the YRBS and is suggested in the NSAM, researchers report. The variations in data may be related to survey design and implementation, they note.

Nonetheless, the declines in sexual experience and the increases in condom use reported in these data indicate shifts toward safer and more self-protective behaviors among adolescents, the researchers conclude. The fact that several surveys show these changes increases confidence that the trends are real, they state.

Trying to understand how the methodological differences in the surveys may affect results might be confusing to the casual reader, says John Santelli, MD, MPH, assistant director for science in the CDC’s Division of Reproductive Health and lead author of the paper. What is reassuring is that the trends are consistent, he notes.

While the just-published analysis offers good news, there are some qualifications, says Susheela Singh, PhD, director of research at the New York City-based Alan Guttmacher Institute (AGI). The findings related to increased condom use and decline in sexual activity among adolescent males are indeed positive, she notes. However, there was much less change in female adolescents, she says.

While the movement toward increased condom use is a welcome one in light of the need for protection against sexually transmitted infections, it is coupled with a decrease in use of oral contraceptives, Singh says. This same finding was recorded in a 1999 paper issued by AGI.3 Increased use of long-acting contraceptives, such as depot medroxyprogesterone acetate (DMPA or Depo-Provera, manufactured by Pharmacia Corp. in Peapack, NJ) and Norplant levonorgestrel implants (manufactured by Wyeth-Ayerst Laboratories in Philadelphia) may be helping protect teens against pregnancy.

"Primarily because of this shift to long-acting methods, overall contraceptive effectiveness among teen-agers improved between 1988 and 1995 — or, put another way, teen-age contraceptive users grew less likely to become pregnant," the AGI paper notes.3

While anecdotal reports signal that use of injectables continues to climb, it will take new data to confirm those findings, says Singh. AGI researchers also are reviewing data to see if adolescents are resorting to noncoital sexual activities instead of intercourse to see if such a switch is contributing to the decline in teen pregnancies.

References

1. Santelli JS, Lindberg LD, Abma J, et al. Adolescent sexual behavior: Estimates and trends from four nationally representative surveys. Fam Plann Perspect 2000; 32:156-165, 194.

2. National Center for Health Statistics. Births: Preliminary Data for 1999. Hyattsville, MD; 2000. (PHS) 2000-1120.

3. Darroch JE, Singh S. Why is Teenage Pregnancy Declining? The Roles of Abstinence, Sexual Activity, and Contraceptive Use. New York: Alan Guttmacher Institute; Occasional Report No. 1, December 1999.