Teen sexual encounters not only a result of unsupervised afternoons

Teen girls reported they were twice as likely to engage in sexual intercourse in the evenings as after school, according to research by Indiana University School of Medicine Adolescent Medicine researchers.

The data from their six-year study was reported in the March issue of the Journal of Adolescent Health.

Researchers followed 106 adolescent women between the ages of 14 and 18 years through annual questionnaires and daily diaries. Each participant completed three questionnaires and multiple 12-week diary entries over a 27-month period. All of the adolescents were from inner-city Indianapolis.

"This data reveals that more than just opportunity plays a role in the frequency of sexual activity among teens," said principal author J. Dennis Fortenberry, M.D., M.S., professor of adolescent medicine and a researcher with the Mid-America Adolescent STD Cooperative Research Center. "I think the take-home message from this study is that more than simple public health solutions are needed to alter such complex behavior."

Dr. Fortenberry and colleagues looked at times and frequency of sexual intercourse and factors that could affect them. Among their findings:

  • Sexual intercourse among adolescent women is relatively infrequent, occurring on about 12 percent of days, according to their study diaries.
  • Intercourse during unsupervised afternoon times accounts for less than one-third of all intercourse events and was less likely to occur on school days than on vacation days
  • Evening/night sex occurred more often on weekends than on vacation days or school days
  • Parental supervision reduced the likelihood of afternoon sex but did not affect the frequency of evening/night sex.
  • Skipping school increased the likelihood of afternoon sex but had no effect on evening sex.

Through the teen's diaries, researchers tracked other elements that might affect frequency or likelihood of sexual intercourse including arguments with partners, general mood, amount of time spent with their partner, sexual activity the previous week and parental monitoring.

The diary entries showed that an argument with a partner increased the likelihood of afternoon sex by about 60 percent, but parental supervision and positive mood decreased the likelihood of afternoon sex by more than 20 percent.

Increased time spent with a partner and more sexual events in the prior week were factors that increased the likelihood of sex in both the afternoon and evening.

Dr. Fortenberry cautioned that generalizations from this data to other populations of adolescent women should be made cautiously. However, the group may provide insight into the sexuality and sexual behaviors of other teen populations.

"Perhaps the most important message from the analyses is the comlexity of adolescent sexuality and adolescent sex," said Dr. Fortenberry. "Public health problems are most easily resolved when only a single risk factor is involved. The conflicts and issues in this research show the multifaceted issues of teen sexuality and may explain why sex and its untoward health consequences have proven resistant to simple interventions, including those focused only on sexual abstinence."


This diary study is part of a larger, continuing study, funded by the National Institute of Allergy and Infectious Disease, a division of the National Institutes of Health.

IU colleagues involved in the research include Margaret Blythe, M.D., Beth A. Juliar, M.A., M.S., Barry P. Katz, Ph.D., Donald Orr, M.D., and Wanzhu Tu, Ph.D.

Last reviewed: By John M. Grohol, Psy.D. on 30 Apr 2016
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