Trends in Frequency of Sexual Activity and Number of Sexual Partners Among Adults Aged 18 to 44 Years in the US, 2000-2018.

Importance: Sexual relationships are important for well-being and health. Recent trends in sexual activity among US adults are unknown. Objectives: To examine trends in reported frequency of sexual activity and number of sexual partners by sex and age and the association between measures of sexual activity and sociodemographic variables. Design, Setting, and Participants: In this survey study, repeat, cross-sectional analyses of participants aged 18 to 44 years from 10 rounds of the General Social Survey (2000-2018), a US nationally representative survey, were performed for men and women separately. Main Outcomes and Measures: Sexual frequency in the past year (sexual inactivity, once or twice per year, 1-3 times per month, or weekly or more) and number of sexual partners in the past year (0, 1, 2, or ≥3 partners). The association between measures of sexual activity and sociodemographic variables were assessed using logistic regression. Results: The study population included 4291 men and 5213 women in the analysis of sexual frequency and 4372 men and 5377 women in the analysis of number of sexual partners (mean [SD] age, 31.4 [7.6] years; survey response rate, 59.5%-71.4%). Between 2000-2002 and 2016-2018, the proportion of 18- to 24-year-old individuals who reported having had no sexual activity in the past year increased among men (18.9% vs 30.9%; age-adjusted odds ratio [aOR] for trend across survey periods, 1.20; 95% CI, 1.04-1.39) but not among women (15.1% vs 19.1%; aOR for trend, 1.03; 95% CI, 0.89-1.18). Smaller absolute increases in sexual inactivity were observed among those aged 25 to 34 years for both men (7.0% vs 14.1%; aOR for trend, 1.23; 95% CI, 1.07-1.42) and women (7.0% vs 12.6%; aOR for trend, 1.17; 95% CI, 1.01-1.35) but not among those aged 35 to 44 years. The increase in sexual inactivity coincided with decreases in the proportion reporting weekly or more sexual frequency (men aged 18-24 years: 51.8% vs. 37.4%; aOR for trend, 0.88 [95% CI, 0.79-0.99]; men aged 25-34 years: 65.3% vs 50.3%; aOR for trend, 0.87 [95% CI, 0.81-0.94]; women aged 25-34 years: 66.4% vs. 54.2%; aOR for trend, 0.90 [95% CI, 0.84-0.96]) or 1 sexual partner (men aged 18-24 years: 44.2% vs. 30.0%; aOR for trend, 0.88 [95% CI, 0.80-0.98]; women aged 25-34 years: 79.6% vs 72.7%; aOR for trend, 0.91 [95% CI, 0.84-0.99]) and occurred mainly among unmarried men (unmarried men aged 18-44 years: 16.2% vs 24.4%; aOR for trend, 1.14 [95% CI, 1.04-1.25]). Among married men and women, weekly or more sexual frequency decreased (men: 71.1 % vs 57.7%; aOR for trend, 0.86 [95% CI, 0.79-0.93]; women: 69.1% vs 60.9%; aOR for trend, 0.92 [95% CI, 0.86-0.99]). Men with lower income (aOR for men with an annual income of ≥$50 000 vs $0-$9999, 0.37 [95% CI, 0.15-0.90]) and with part-time (aOR vs full-time employment, 2.08; 95% CI, 1.48-2.93) and no employment (aOR vs full-time employment, 2.08; 95% CI, 1.48-2.93) were more likely to be sexually inactive, as were men (aOR vs full-time employment, 2.94; 95% CI, 2.06-4.21) and women (aOR vs full-time employment, 2.37; 95% CI, 1.68-3.35) who were students. Conclusions and Relevance: This survey study found that from 2000 to 2018, sexual inactivity increased among US men such that approximately 1 in 3 men aged 18 to 24 years reported no sexual activity in the past year. Sexual inactivity also increased among men and women aged 25 to 34 years. These findings may have implications for public health.