BLOOMINGTON, Ind. -- Sexual frequency is declining in the United States, according to a study by Indiana University researchers.
"Our study adds to a growing body of research that has reported on declines in sex," said Tsung-chieh "Jane" Fu, a research associate at the IU School of Public Health-Bloomington who co-led the study. "The declines in partnered sexual activity seen in our study are consistent with findings from studies in the U.K., Australia, Germany and Japan."
Debby Herbenick, a professor of sexual and reproductive health at the School of Public Health who also co-led the study, said the decreases are likely caused by several factors.
"The decreases are not easily explained by a single shift, such as health status, technology, access to pornography or stress," Herbenick said. "There are likely multiple reasons for these changes in sexual expression, and we need more research to understand how these changes may be related to changes in relationships, happiness and overall well-being."
The study of sexual frequency is particularly important in light of the COVID-19 pandemic's impacts on relationships, Herbenick said. Declining sexual activity among adults has consequences for human fertility and health -- consequences that have been exacerbated by pandemic-era restrictions.
Published in the Archives of Sexual Behavior, the study is the first to include such a comprehensive assessment of diverse sexual behaviors. The information came from U.S. participants ages 14 to 49 during the 2009 and 2018 waves of the National Survey of Sexual Health and Behavior, a confidential nationally representative survey conducted online. A total of 1,647 adolescents ages 14 to 17 and 7,055 adults ages 18 to 49 were included.
"The National Survey of Sexual Health and Behavior includes detailed data on a variety of sexual behaviors, so we could examine more precisely whether declines in vaginal intercourse might be explained by increases in other sexual behaviors, such as oral sex," Herbenick said. "However, we found that was not the case. Rather, we found that from 2009 to 2018, fewer adults engaged in a range of partnered sexual activities. We were also surprised to find that, among adolescents, both partnered sex and solo masturbation had declined."
Compared to adult participants in the 2009 survey, adults in the 2018 group were significantly more likely to report no penile-vaginal intercourse in the prior year, the researchers found. Study participants were also significantly less likely to report engaging in any other sexual behaviors examined in the study, such as oral sex or anal sex. All modes of past-year partnered sex were reported by fewer people in the 2018 cohort.
"More studies are needed to understand if this decline is associated with the emergence of other types of sexual activities in recent years, such as the adverse impact of what some people call aggressive or rough sex," Fu said.
The study's findings regarding sexual frequency declines among adolescents are particularly notable, according to Herbenick. The proportion of adolescents reporting neither solo masturbation nor partnered sexual behavior increased from 28% of young men and 49% of young women in 2009 to 43% of young men and 74% of young women in 2018.
"Many studies haven't included those under age 16 or 18, so our study expands what we know about younger adolescent behavior and how we think about adolescent sexual development," Herbenick said.
The researchers noted that a number of cultural and social changes may be affecting young people's sexual behavior, including widespread internet access, decreased alcohol use, increased conversations around sexual consent, and more contemporary young people identifying with non-heterosexual identities, including asexual identities.
While the current findings will help inform the work of sexual health researchers, clinicians and educators, Herbenick said she hopes the study also will open up new investigations into areas such as people's feelings about their sexual lives and how those feelings may shape subsequent choices about sex.