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. Author manuscript; available in PMC: 2010 Jan 4.
Published in final edited form as: Obesity (Silver Spring). 2008 Aug 14;16(11):2552–2555. doi: 10.1038/oby.2008.394

Obesity and the Likelihood of Sexual Behavioral Risk Factors for HPV and Cervical Cancer

Christina C Wee 1, Annong Huang 1, Karen W Huskey 1, Ellen P McCarthy 1
PMCID: PMC2801345  NIHMSID: NIHMS156072  PMID: 18719677

Abstract

Obesity is associated with higher cervical cancer mortality, but its relationship with sexual behavioral risk factors that predispose women to human papilloma virus (HPV) and cervical cancer is unclear. We used data from 3,329 women participants, aged 20–59 years, of the 1999–2004 National Health and Nutrition Examination Survey, to analyze the relationship between BMI and age at first intercourse, number of sexual partners, condom use during sexual activity, history of sexually transmitted disease (STD), herpes simplex virus 2 (HSV-2) seropositivity, and HPV prevalence. BMI was not associated with the prevalence of HPV. Mildly obese women (BMI 30.0–34.9 kg/m2) were least likely to report a STD history (9% vs. 13% in normal weight) and ≥2 sexual partners in the previous year (8% vs. 13%) while overweight women (BMI 25.0–29.9 kg/m2) were least likely to report ≥10 lifetime partners; among those with multiple partners, BMI was not associated with sexual activity without condoms in the past month. After adjustment for age, race/ethnicity, and education, women with higher BMI were less likely to report sexual behavioral risk factors than normal-weight women; however, odds ratios were only significant for mildly obese women for reporting a STD history (0.74, 95% confidence interval 0.55–0.99) and having ≥2 sexual partners in the last year (0.57, 0.39–0.85). Higher BMI was not associated with HSV-2 seropositivity after adjustment. HPV and sexual behavioral risk factors for HPV and cervical cancer are not more prevalent in obese than normal-weight women and unlikely to account for higher-observed cervical cancer mortality in obese women.

Obesity is associated with a higher risk of cancer death including deaths from cervical cancer (1). Each year, almost 10,000 women in the United States are diagnosed with invasive cervical cancer and another 4,000 women die from the disease (2). Women who are moderately to severely obese are more than three times as likely to die from cervical cancer as women with normal body weight (1).

The excess mortality from cervical cancer associated with obesity is especially astounding given that cervical cancer is largely a preventable disease. Regular screening using the Papanicolaou test has been effective in reducing the incidence of this disease in developed countries (3,4). However, despite their higher cancer risk, evidence suggests that women with obesity are less likely to report timely screening for cervical cancer (5,6). Hence, lower adherence to screening recommendations may contribute to the higher risk of premature death from cervical cancer observed among obese women.

The human papilloma virus (HPV) is central to the development of cervical cancer (7) and has become increasingly prevalent (8). Some of these infections are transient but a fraction of these do lead to cervical changes that progress to cervical cancer if not detected and treated early. There are also several serotypes of HPV, some conferring higher risk of malignancy than others (9,10). HPV is transmitted through sexual activity, and several modifiable factors have been identified that place women at higher risk for contracting HPV and in turn lead to higher risk of cervical cancer. These factors include many ameliorable behaviors such as early onset of sexual activity, having multiple sexual partners, and previous sexually transmitted disease (STD) (11–16). Few studies have examined whether the psychosocial consequences of obesity impacts the sexual behaviors of obese individuals, particularly high-risk behaviors that might place women at risk for HPV infection and thus cervical cancer (17).

In this context, we examined the association between obesity and the prevalence of several cervical cancer risk factors reported by participants in the 1999–2004 National Health and Nutrition Examination Study (NHANES) to understand better the contribution of sexual behavioral risk factors to the higher-observed cervical cancer mortality among women with obesity.

METHODS

NHANES is a stratified multistage probability sample of the noninstitutionalized civilian population of the United States conducted by the Centers for Disease Control and Prevention and the National Center for Health Statistics (18). NHANES is designed to assess the health and nutritional status of adults and children and combines both interviews and physical examination. Beginning in 1999, the study was redesigned to be an ongoing continuous program. Data are released in 2-year cycles. Design weights and sampling information are provided so that analyses that account for the complex sampling design can be generalized to the US population.

As part of the interview, participants aged 20–59 years were asked a series of questions about their health and sexual behavior. We restricted our study sample to women participants in this age group (n = 4,132). Questions elicited whether women ever had sexual intercourse, the age at which they first had sexual intercourse, and the number of sexual partners in the past month, in the past year, and in their lifetime. Among women who reported sexual activity in the previous month (n = 408), they were asked the number of times they had intercourse without using a condom. Participants were also asked about having been diagnosed with a STD, namely genital herpes, genital warts, gonorrhea, and chlamydia (“Has a doctor ever told you that you had …”). In addition, women were also asked about demographic information including age, race and ethnicity, and educational level.

All participants underwent physical and laboratory examinations in mobile examination units. Height and weight were measured, which we used to calculate BMI. We then categorized participants according to standard weight categories (19): normal weight or BMI of 18.5–24.9 kg/m2 (served as our reference group), overweight or BMI of 25.0–29.9 kg/m2, class I obesity or BMI 30.0–34.9 kg/m2, and class II–III obesity or BMI 35.0 kg/m2 and higher. We excluded women who were missing either height or weight (n = 52) as well as women who were underweight (BMI <18.5 kg/m2) (n = 80) or who were pregnant by history (n = 661) because body weight in these situations may not reflect stable baseline weights. Blood samples were collected and tested for herpes simplex virus 2 (HSV-2) antibodies in women aged 20–49 years. HSV-2 is the cause of most cases of genital herpes, a STD. A positive antibody test (seropositivity) indicates previous infection.

Female respondents to the 2003–2004 NHANES were also asked to submit self-collected cervicovaginal swabs. DNA was extracted using modifications of the QIAmp Mini Kit protocol within one month of sample collection, and HPV detection and typing was conducted as described elsewhere (8). Between January 2003 and April 2004, probes were performed for 27 HPV serotypes including those that were high risk (16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68, 73, 82) and low risk (6, 11, 40, 42, 54, 55, 83, 84) for cervical cancer. After April, additional high- (67, 69, 70, IS39) and low-risk (61, 62, 64, 71, 72, 81, 89) serotypes were probed.

Data analysis

We used bivariable and multivariable statistical analytic methods to examine the relationship between BMI category and several risk factors of HPV infections and cervical cancer: age at first intercourse, having any history of STD (genital herpes, genital warts, gonorrhea, and chlamydia), number of lifetime partners (≥10 partners), whether or not women had two or more partners in the previous year. Among those with two or more partners in the previous year who were also sexually active in the preceding month, we examined the relationship between BMI and reporting not using condoms at least one or more times in the preceding month. Finally in the subgroup who submitted adequate cervicovaginal swabs, we studied the association between BMI and HPV infection. Models were adjusted for age, race/ethnicity, and education level. We weighted analyses to reflect US population estimates and used SUDAAN analytic software (20) to account for the complex stratified sampling scheme so that appropriate standard errors are derived.

RESULTS

Table 1 characterizes our study sample. Of 3,329 nonpregnant women aged 20–59 years who had a BMI of ≥18.5 kg/m2, 39% were normal weight, 27% were overweight, and 34% were obese. Normal-weight women were significantly younger, were more likely to be non-Hispanic white, and completed more years of formal education.

Table 1.

sample characteristics by BMI (n = 3,329)

BMI, kg/m2 18.5–24.9 25.0–29.9 30.0–34.9 ≥35.0
Sample size (%) 1,135 (38.6) 929 (26.9) 659 (17.7) 606 (16.8)
Mean age*, years 38.1 41.5 41.6 42.9
Race/Ethnicity*, %
 White 79 68 65 66
 African-American 6 12 17 20
 Mexican-Hispanic 5 8 9 7
 Other hispanic 4 7 8 6
 Other race 5 4 1 1
Education*, %
 <High school 10 17 22 17
 High school graduate 23 25 25 28
 >High school 67 58 53 55
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*

P < 0.001.

Figure 1 characterizes women’s sexual behavioral risk factors according to BMI before adjustment. Compared to normal-weight women, women with higher BMI were significantly less likely to have two or more sexual partners in the previous year. Obese women with a BMI between 30.0 and 34.9 kg/m2 were the least likely to report a prior history of STD, P = 0.04; however, women with higher-than-normal BMI had higher rates of HSV-2 seropositivity. Age of intercourse, number of lifetime partners, and condom use did not significantly differ across BMI. BMI was also not significantly associated with active HPV prevalence; these results were consistent when we limited the outcome to include only high-risk HPV serotypes.

Figure 1.

Figure 1

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Prevalence of sexual behavioral risk factors across BMI.

*Sex without a condom was only assessed among those with ≥2 sexual partners in the previous year. **HPV is available for the 2003–2004 assessment only.

After adjustment for age, race and ethnicity, and educational level (Table 2), women with higher-than-normal BMI in general were less likely to report higher-risk sexual behaviors. These results, however, did not achieve statistical significance except in women with BMIs between 30.0 and 34.9 kg/m2 who were less likely to report a history of STD or having two or more sexual partners in the previous year. HPV prevalence did not differ by BMI after adjustment.

Table 2.

odds ratio (95% confidence interval) for sexual behavioral risk factors

≤16 years of age at first intercourse (n = 3,320) ≥10 Lifetime partners (n = 3,328) ≥2 Partners last year (n = 3,326) Sex without condom in the past month (n = 331) History of STD (n = 3,327) HSV-2 seropositivity (n = 2,435) HPVa (n = 990)
BMI, kg/m2
 18.5–24.9 1.00 1.00 1.00 1.00 1.00 1.00 1.00
 25.0–29.9 1.24 (0.98, 1.57) 0.79 (0.62, 1.01) 0.78 (0.57,1.08) 0.93 (0.38, 2.26) 1.13 (0.82, 1.55) 1.06 (0.75–1.51) 0.99 (0.74, 1.33)
 30.0–34.9 1.13 (0.87, 1.48) 0.88 (0.65, 1.20) 0.57 (0.39, 0.85) 0.66 (0.32, 1.37) 0.74 (0.55, 0.99) 0.98 (0.64–1.52) 1.34 (0.99, 1.81)
 ≥35.0 1.11 (0.84, 1.46) 0.95 (0.73, 1.23) 0.82 (0.56, 1.22) 0.82 (0.36, 1.86) 0.99 (0.65, 1.51) 0.93 (0.70–1.23) 0.78 (0.49, 1.23)
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Results adjusted for age, race/ethnicity, and education.

a

Available for the 2003–2004 NHANES participants only.

DISCUSSION

Our study found that the prevalence of HPV did not vary by BMI. Women with a higher BMI were no more likely to report sexual behavioral risk factors that might predispose them to acquiring HPV infection and developing cervical cancer. Compared to normal-weight women, women with a higher BMI were as or less likely to report previous STD, had comparable numbers of lifetime partners, and were as or less likely to have two or more sexual partners in the previous year; among those with multiple partners in the previous year, heavier women were no more likely to have sexual intercourse without condoms in the previous month. After adjusting for sociodemographic factors, heavier women were also no more likely than normal-weight women to demonstrate objective evidence of previous genital herpes infection.

Beyond its association with adverse health consequences, obesity has been shown to result in profound psychosocial consequences (21). Studies suggest that obese individuals are often viewed as less desirable dating and courtship partners (21–24) and have difficulty entering into romantic and marriage relationships (21,25–27). Obese women tend to marry later and marry less desirable partners even though they do not have lower marital aspirations than thinner women (28). However, few studies have examined whether the social stigma associated with obesity actually affects sexual behavior, particularly high-risk sexual behavior. A recent analysis by Nagelkerke et al. (17) using the 1999 and 2000 NHANES sample found that obese men reported fewer lifetime sexual partners than thinner men but did not find a similar relationship in women; however, their sample was only a third the size of ours. Nagelkerke et al. also examined the relationship between BMI and HSV-2 seropositivity, but because of limited sample size, could not examine obesity’s relationship with other STDs or other high-risk sexual behaviors. Our study confirms the lack of relationship between obesity and the number of lifetime sexual partners in Nagelkerke et al.’s earlier work and extends this earlier work in a larger national sample to include other sexual behaviors such as the age of first intercourse, common STDs, and the likelihood of sexual activity without using a condom. We also found that the prevalence of HPV did not vary by BMI. The high prevalence of HPV in the general population (8) may have masked any variation by BMI.

Given our findings, higher death rates from cervical cancer in obese women compared to normal women are unlikely to be due to a higher underlying risk of HPV infection which is a necessary precursor to developing cervical cancer. Rather, higher mortality from cervical cancer among obese women likely reflects lower rates of screening documented by other studies (5,6). Although the absolute difference in screening rates are modest, we estimated previously (5) that a reduction of 3.5 and 6% in screening in overweight and obese women during a 3-year screening interval would lead to ~1,200 cases of missed or delayed diagnoses of invasive cervical cancer, highlighting the importance of targeting efforts at improved screening.

Although HPV infection is a necessary precursor to the development of cervical cancer, women who are exposed and become infected with HPV do not necessarily develop the disease. In many women, especially those who were exposed at younger ages, the infection becomes undetectable over time (29,30). Moreover, the cervical changes that are produced by HPV progress through several stages before malignancy results (30). Hence, cervical cancer can be avoided if these cervical changes are detected early enough and intervened upon through biopsy and colposcopy procedures before the lesions develop into cervical cancer (30). Whether obese women are less likely than thinner women to obtain proper follow-up evaluation and treatment once either HPV or HPV-associated cervical changes are detected has not been studied.

Our study should be interpreted in the context of its limitations. First, the cross-sectional and observational design prevents us from drawing causal inferences about the relationship between obesity and high-risk sexual behaviors. This is particularly the case in the outcome of prior behaviors and STDs because we have no information on respondents’ BMI at the time of the past behaviors, although there is likely a strong correlation between past weight and current weight. Second, sexual behavioral characteristics were assessed exclusively by self-report and consequently there is likely under-reporting of socially undesirable behaviors such as high-risk sexual behaviors; the NHANES does, however, use an audio computer- assisted survey interviewer which has been shown to improve the quality of self-reported data on socially undesirable behavior (31). Moreover, there is no evidence that any under- reporting should occur differentially by BMI and given that the estimates for high-risk behavior for higher-weight women were consistently lower than their normal-weight counterpart, it is unlikely that a strong enough weight-related reporting bias exists that would have altered our conclusions.

In summary, despite the higher risk of death from cervical cancer observed among women with higher BMI, obesity was not associated with a higher prevalence of HPV or with sexual behavioral risk factors that might predispose women to developing HPV infection and cervical cancer. Higher risk of death from cervical cancer among obese women are more likely to be due to previously described disparities in cancer screening than to differences in underlying behavioral risk factors.

Acknowledgments

The study was funded by a grant from the National Institutes of Health/National Institutes of Diabetes and Digestive and Kidney Diseases (R01 DK071083). We thank the Centers for Disease Control (CDC) and National Center for Health Statistics (NCHS) for providing the initial data. The analyses, interpretations, and conclusions are those of the authors, however, and do not reflect the views or opinions of the CDC, NCHS, or National Institutes of Health. The funder had no role in the analysis of data or the interpretations and conclusions of the authors. We also thank Norma Ojehomon for administrative and editorial assistance.

Footnotes

DISCLOSURE

The authors declared no conflict of interest.

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