The findings of the research by researchers at the Bradley Hasbro Children's Research Center reflect recent data indicating that anal sex rates among adults doubled between the years 1995 and 2004.
Being one of the first of its kind, the study has highlighted the little-known factors linked with heterosexual anal intercourse among adolescents and young adults.
"The topic of anal intercourse is often considered taboo - especially when discussed in the context of youth relationships - even though we know that this behavior is a significant risk factor for HIV and other sexually transmitted infections. It's critical that we recognize that more and more young people are engaging in anal sex so we can open the lines of communications and help them protect their sexual health," said lead author Celia Lescano, PhD, of the Bradley Hasbro Children's Research Center (BHCRC).
In the study, the scientists examined sexual behaviour of 1,348 adolescents and young adults between the ages of 15 and 21 who had unprotected sex in the previous three months.
It was found that 16 percent had engaged in heterosexual anal intercourse within the timeframe, with condoms being used just 29 percent of the time.
Females who had heterosexual anal sex were more likely to be living with their partners, to have two or more sexual partners and to have previously experienced coerced intercourse.
Males who engaged in heterosexual anal intercourse were more likely to identify themselves as being homosexual, bisexual or undecided.
"These findings suggest that the factors associated with anal intercourse among females in the study relate to the context and power balance of sexual relationships. We must teach teen girls and young women how to be assertive in sexual relationships, such as refusing unwanted sexual acts and negotiating for safer sex, whether it's anal or vaginal," said Lescano, who's also an assistant professor of psychiatry (research) at the Warren Alpert Medical School of Brown University.
But, many factors related to anal intercourse were found to be consistent in both genders.
Generally, those who felt that using condoms decreased the pleasure of sex and those who used drugs at the time of intercourse were engaged in riskier behaviours.
Such behaviours indicated that interventions should emphasize that sex can be both pleasurable and safe.
"An open dialogue between health care providers and their young patients about anal intercourse is becoming increasingly important, and clinicians should ask about anal sex during discussions about vaginal intercourse and protection - regardless of the patient's gender or reported sexual orientation," said Lescano.
The American Journal of Public Health publishes the study online.