Background Examining national trends in sexual behaviour can aid in the understanding of STD trends. We examined trends in sexual behaviour, focusing on sub-populations most impacted by STDs in the US.

Methods We used data from the 2002 and 2006–10 National Survey of Family Growth (NSFG), a multi-stage survey nationally representative of men and women aged 15–44 years living in the United States (US). The sample sizes and response rates for the surveys were 12, 571 (79%) in 2002 and 22,682 (77%) in 2006–10. Sexual behaviours included in this analysis were predominantly from audio computer assisted self-interview and were compared by several demographics, separately by sex. Data were weighted to represent the US population and data analyses accounted for the multi-staged sampling procedures used by NSFG.

Results Sexual behaviours with opposite- and same-sex partners were frequently similar in 2002 and 2006–10. Of women who ever had vaginal sex, there was no change in the average number of partners in the past 12 months (1.21 in 2002, 1.11 in 2006–10); however there was a slight decrease over time for Hispanic and black women and a slight increase among women in the non-Hispanic other category. Findings for men were similar except for a slight increase in partners among white men. Overall, HIV-related risk with opposite-sex partners decreased from 2002 to 2006–10. Specifically, exchanging sex for money or drugs significantly decreased among women (2.0% to 0.7%, p < 0.05) and men (2.6% to 1.3%, p < 0.05). Finally, the average number of male partners decreased among sexually active men who have sex with men (MSM) from 2.9 in 2002 to 2.3 in 2006–10 (p < 0.05). Specific HIV risk also declined among MSM.

Conclusion Preliminary findings suggest that behaviours have not changed much during this time; however, we did identify shifts in behaviours among sub-populations.