Understanding sexual behavior is crucial for public health initiatives, especially in the realm of sexually transmitted infections (STIs). Data-driven insights into patterns of sexual activity can significantly aid in prevention strategies and resource allocation. This article delves into findings from the National Survey of Family Growth (NSFG) conducted between 2006 and 2010, shedding light on the distribution of sexual behaviors in the United States, categorized by lifetime vaginal sex partners. While the term “average sexual partners” can be statistically misleading due to variations in reporting and behavior, this research provides valuable context by examining sexual activity groups and their associated behaviors.
This study, utilizing a nationally representative sample of 15- to 44-year-olds, aimed to explore the nuances of sexual behavior by stratifying participants into five distinct sexual activity groups based on their reported lifetime number of vaginal sex partners. These groups, ranging from 0-1 partner to 40+ partners, offer a more detailed picture than simply looking at an overall “average sexual partner” statistic. By analyzing these groups, researchers uncovered key trends related to recent sexual activity and age at sexual debut, providing valuable data for STI prevention and for informing mathematical models used to understand STI transmission dynamics.
Diving into Sexual Activity Groups: A Spectrum of Experience
The NSFG data allowed researchers to categorize participants into the following sexual activity groups:
- Group 1 (0–1 Lifetime Partners): Individuals reporting zero or one lifetime vaginal sex partner.
- Group 2 (2–4 Lifetime Partners): Individuals reporting two to four lifetime vaginal sex partners.
- Group 3 (5–9 Lifetime Partners): Individuals reporting five to nine lifetime vaginal sex partners.
- Group 4 (10–39 Lifetime Partners): Individuals reporting ten to thirty-nine lifetime vaginal sex partners.
- Group 5 (40+ Lifetime Partners): Individuals reporting forty or more lifetime vaginal sex partners.
These groupings, while seemingly broad, are instrumental in highlighting the heterogeneity of sexual behavior within the population. It’s important to note that “sex partners” in this study specifically refers to heterosexual vaginal intercourse partners, excluding same-sex partners to focus on vaginal sex in a lifetime context.
Distribution of Lifetime Partners Across Age and Gender
Analyzing the distribution of participants across these groups revealed some interesting patterns when broken down by age and gender.
For both men and women aged 15-24, Sexual Activity Group 1 (0-1 lifetime partner) was the most common category. This is visually represented in Figure 1A and 1B, showing that for younger individuals, a significant portion reported having had very few or no vaginal sex partners.
[](https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Distribution of lifetime sex partners among women and men by age group, NSFG 2006–2010.)
Interestingly, as age increased, the most frequently reported group shifted. For women aged 25-44, Sexual Activity Group 2 (2-4 lifetime partners) became the most common. In contrast, for men in the same age range (25-44), Sexual Activity Group 4 (10-39 lifetime partners) was most frequently reported. This suggests a divergence in reported lifetime partners as individuals age, with men more likely to report a higher number of lifetime partners in older age groups compared to women in this study. Sexual Activity Group 5 (40+ lifetime partners) remained the least frequently reported group across all age categories for both sexes, indicating that reporting a very high number of lifetime partners is less common in the general population.
Recent Sexual Partners: Is Past Behavior Predictive?
The study further investigated the connection between lifetime sexual partners and recent sexual activity by examining the average number of sex partners in the past 12 months within each sexual activity group. Figure 2A and 2B illustrate these findings.
[](https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Number of sex partners in the past 12 months among women and men by age group and sexual activity group, NSFG 2006–2010.)
A clear trend emerged: individuals in higher lifetime partner groups reported a higher average number of recent partners. Specifically, those in Sexual Activity Group 1 (0-1 lifetime partner) averaged less than one recent partner. Conversely, participants in Sexual Activity Group 5 (40+ lifetime partners) reported a significantly higher range of recent partners, from 1.5 to 5.1, depending on age. While men overall reported slightly more recent partners than women, within each sexual activity group, the difference between genders was not statistically significant, highlighting that lifetime partner group is a stronger predictor of recent activity than gender alone within these categories.
This data underscores that past sexual behavior, as reflected in lifetime partner numbers, can be a useful indicator of recent sexual activity levels. It suggests that individuals with a history of more sexual partners are also more likely to have more partners in a given year.
Age at First Intercourse: An Early Start, More Partners Later?
Another aspect explored was the age at first vaginal intercourse in relation to lifetime sexual partners. The study focused on individuals aged 25-34 to assess age at first intercourse in more recent years, providing data more relevant to current STI prevention efforts. Figure 3A and 3B present these findings.
Figure 3](https://www.ncbi.nlm.nih.gov/core/lw/2.0/html/tileshop_pmc/tileshop_pmc_inline.html?title=Age at first vaginal intercourse among women and men aged 25 to 34 years by sexual activity group, NSFG 2006–2010.)
The data revealed a general trend: individuals with higher lifetime partner numbers reported a younger age at first vaginal intercourse. This relationship was consistent for both men and women. For most sexual activity groups, the reported ages at first intercourse were similar between genders. However, within Sexual Activity Group 1 (0-1 lifetime partner), a notable difference emerged: men were more likely to report their first intercourse at ages 18-24 compared to women in the same group.
This finding suggests a correlation between earlier sexual debut and a higher number of lifetime sexual partners. Individuals who initiated vaginal intercourse at a younger age tended to accumulate more partners over their lifetime. This information is pertinent for understanding the trajectory of sexual behavior and its potential implications for STI risk.
Implications for STI Prevention and Modeling
This research reinforces the idea that lifetime number of sexual partners, while not a perfect measure, offers a valuable and simple way to categorize individuals based on their sexual activity level. Understanding these sexual activity groups and their associated behaviors can be instrumental in several areas:
- Targeted STI Prevention: By recognizing that individuals in higher sexual activity groups are more likely to have recent partners and potentially earlier sexual debut, public health initiatives can tailor prevention strategies and resource allocation to these groups. This can lead to more effective screening programs, educational campaigns, and interventions.
- Informing Mathematical Models: Mathematical models are increasingly used to understand and predict STI transmission dynamics. Data on sexual behavior, particularly categorized by sexual activity levels, is crucial for these models. This study provides valuable data points for refining these models and improving their accuracy in simulating real-world scenarios.
- Understanding Epidemiological Trends: National data on sexual behavior helps track trends in sexual activity over time. This information is vital for monitoring changes in STI incidence and prevalence, allowing for timely adjustments in public health strategies.
While the concept of “average sexual partners” may oversimplify the complexities of human sexual behavior, this study demonstrates the utility of examining sexual activity groups based on lifetime partners. It provides a more nuanced and data-driven approach to understanding sexual behavior patterns and their implications for public health, particularly in the context of STI prevention.
Acknowledgments:
This research was supported in part by an appointment to the Research Participation Program at the Centers for Disease Control and Prevention administered by the Oak Ridge Institute for Science and Education.
References:
[List of references from original article – ensure these are included in the final output]
Appendix Tables (A1, A2, A3):
[Include Appendix Tables A1, A2, and A3 as provided in the original article in markdown table format]
TABLE A1.
Distribution of the Number of Lifetime Sex Partners, by Age Group and Sex, NSFG 2006–2010
| AgeGroup, y | Lifetime SexPartners | Women (n = 12,279) | Men (n = 10,403) |
|---|---|---|---|
| Unweighted n | PopulationEstimate | ||
| 15–19 | 0–1 partner | 1592 | 7,541,000 |
| 2–4 partners | 435 | 1,805,0000 | |
| 5–9 partners | 191 | 828,000 | |
| 10–39 partners | 65 | 54,000 | |
| 40+ partners | —* | — | |
| 20–24 | 0–1 partner | 660 | 3,599,000 |
| 2–4 partners | 626 | 2,987,000 | |
| 5–9 partners | 487 | 2,425,000 | |
| 10–39 partners | 308 | 1,260,000 | |
| 40+ partners | 17 | 94,000 | |
| 25–29 | 0–1 partner | 555 | 2,625,000 |
| 2–4 partners | 712 | 3,219,000 | |
| 5–9 partners | 603 | 2,528,000 | |
| 10–39 partners | 444 | 1,955,000 | |
| 40+ partners | 52 | 208,000 | |
| 30–34 | 0–1 partner | 431 | 2,040,000 |
| 2–4 partners | 605 | 2,836,000 | |
| 5–9 partners | 521 | 2,268,000 | |
| 10–39 partners | 437 | 1,851,000 | |
| 40+ partners | 53 | 193,000 | |
| 35–39 | 0–1 partner | 379 | 2,454,000 |
| 2–4 partners | 550 | 3,188,000 | |
| 5–9 partners | 492 | 2,902,000 | |
| 10–39 partners | 339 | 1,839,000 | |
| 40+ partners | 38 | 154,000 | |
| 40–44 | 0–1 partner | 321 | 2,295,000 |
| 2–4 partners | 499 | 3,246,000 | |
| 5–9 partners | 504 | 3,141,000 | |
| 10–39 partners | 318 | 1,729,000 | |
| 40+ partners | 44 | 240,000 |
TABLE A2.
Number of Sex Partners in the Past 12 Months by Age Group, Sex, and Sexual Activity Group (Lifetime Number of Sex Partners), NSFG 2006–2010
| Age Group, y | Women (n = 12,278*) | Men (n = 10,403) |
|---|---|---|
| Mean | 95% CI | |
| No. sex partners, past 12 mo (for all sexual activity groups) | ||
| 15–19 | 1.56 | 1.45–1.67 |
| 20–24 | 1.31 | 1.25–1.38 |
| 25–29 | 1.17 | 1.13–1.22 |
| 30–34 | 1.07 | 1.01–1.12 |
| 35–39 | 0.99 | 0.96–1.02 |
| 40–44 | 0.94 | 0.91–0.98 |
| Sexual activity group 1 (0–1 lifetime sex partners) | ||
| 15–19 | 0.86 | 0.81–0.91 |
| 20–24 | 0.86 | 0.81–0.90 |
| 25–29 | 0.90 | 0.86–0.94 |
| 30–34 | 0.90 | 0.86–0.95 |
| 35–39 | 0.90 | 0.85–0.94 |
| 40–44 | 0.89 | 0.85–0.93 |
| Sexual activity group 2 (2–4 lifetime sex partners) | ||
| 15–19 | 1.47 | 1.36–1.59 |
| 20–24 | 1.12 | 1.04–1.19 |
| 25–29 | 0.98 | 0.94–1.01 |
| 30–34 | 0.92 | 0.89–0.96 |
| 35–39 | 0.95 | 0.89–1.02 |
| 40–44 | 0.86 | 0.82–0.91 |
| Sexual activity group 3 (5–9 lifetime sex partners) | ||
| 15–19 | 2.58 | 2.30–2.86 |
| 20–24 | 1.49 | 1.36–1.62 |
| 25–29 | 1.18 | 1.11–1.25 |
| 30–34 | 1.03 | 0.98–1.07 |
| 35–39 | 1.00 | 0.97–1.03 |
| 40–44 | 0.93 | 0.89–0.98 |
| Sexual activity group 4 (10–39 lifetime sex partners) | ||
| 15–19 | 2.90 | 2.24–3.56 |
| 20–24 | 2.09 | 1.80–2.38 |
| 25–29 | 1.64 | 1.49–1.80 |
| 30–34 | 1.37 | 1.20–1.53 |
| 35–39 | 1.09 | 1.00–1.18 |
| 40–44 | 1.09 | 0.98–1.21 |
| Sexual activity group 5 (40+ lifetime sex partners) | ||
| 15–19 | —† | — |
| 20–24 | 2.89 | 2.11–3.66 |
| 25–29 | 2.57 | 1.83–3.31 |
| 30–34 | 2.28 | 0.90–3.66 |
| 35–39 | 1.97 | 1.30–2.64 |
| 40–44 | 1.61 | 1.16–2.07 |
TABLE A3.
Age at First Vaginal Intercourse for Those Aged 25 to 34 Years by Sex and Sexual Activity Group (Lifetime Number of Sex Partners), NSFG 2006–2010
| Age at First Vaginal Intercourse, y | Women (n = 4090) | Men (n = 3362) |
|---|---|---|
| Unweighted n | Population Estimate | |
| Age at first vaginal sex (for all sexual activity groups) | ||
| 10–14 | 684 | 2,778,000 |
| 15 | 583 | 2,670,000 |
| 16 | 742 | 3,518,000 |
| 17 | 587 | 2,489,000 |
| 18–24 | 1,494 | 6,892,000 |
| Sexual activity group 1 (0–1 lifetime sex partners) | ||
| 10–14 | 15 | 32,000 |
| 15 | 42 | 164,000 |
| 16 | 52 | 241,000 |
| 17 | 74 | 329,000 |
| 18–24 | 539 | 2,746,000 |
| Sexual activity group 2 (2–4 lifetime sex partners) | ||
| 10–14 | 128 | 539,000 |
| 15 | 160 | 796,000 |
| 16 | 235 | 1,222,000 |
| 17 | 219 | 982,000 |
| 18–24 | 548 | 2,410,000 |
| Sexual activity group 3 (5–9 lifetime sex partners) | ||
| 10–14 | 228 | 834,000 |
| 15 | 207 | 955,000 |
| 16 | 255 | 1,203,000 |
| 17 | 177 | 721,000 |
| 18–24 | 244 | 1,058,000 |
| Sexual activity group 4 (10–39 lifetime sex partners) | ||
| 10–14 | 261 | 1,205,000 |
| 15 | 161 | 684,000 |
| 16 | 184 | 783,000 |
| 17 | 108 | 406,000 |
| 18–24 | 153 | 644,000 |
| Sexual activity group 5 (40+ lifetime sex partners) | ||
| 10–14 | 52 | 169,000 |
| 15 | 13 | 70,000 |
| 16 | 16 | 69,000 |
| 17 | —* | — |
| 18–24 | 10 | 35,000 |
