A study conducted by researchers at the University of Illinois at Chicago, published in the May/June issue of the journal Child Development, analyzed data on 1,350 15- to 18-year-old male and female students taking part in the National Longitudinal Study of Adolescent Health, a nationwide study of individual, peer, family, school and community factors related to health.
Adolescents whose friends had intercourse without a condom were more likely to have intercourse without a condom the following year. Those whose friends believed that sex had undesirable consequences were likely to change attitudes to be similar to those of their friends and were less likely to have intercourse without a condom the following year, the study found.
Other findings showed that adolescents choose new friends with attitudes similar to their own. Teens who believed that sex had undesirable consequences were likely to choose new friends and retain existing friends with similar attitudes, according to lead author David B. Henry.
High-risk sexual behavior was defined by the number of partners with whom adolescents had had intercourse without a condom.