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Prevalence and Motivation: Pubic Hair Grooming Among Men in the United States

Pubic hair grooming is a growing phenomenon and is associated with body image and sexual activity. A nationally representative survey of noninstitutionalized adults aged 18 to 65 years residing in the United States was conducted. Differences in demographic and sexual characteristics between groomers and nongroomers were explored. Four thousand one hundred and ninety-eight men completed the survey. Of these men, 2,120 (50.5%) reported regular pubic hair grooming. The prevalence of grooming decreases with age, odds ratio = 0.95 (95% confidence interval [0.94, 0.96]), p < .001. Adjusting for sexual frequency and sexual orientation, grooming is associated with performing and receiving oral sex. The majority of men report grooming in preparation for sexual activity with a peak prevalence of 73% among men aged 25 to 34 years, followed by hygiene (61%) and routine care (44%). The majority of men who remove their pubic hair groom the hair above the penis (87%), followed by the scrotum (66%) and the penile shaft (57%). Overall, pubic hair grooming is common among men aged 18 to 65 years in the United States. Younger ages are associated with greater rates of pubic hair grooming. Many men groom for sex, in particular oral sex, as well as for routine care and hygiene.


Introduction
Pubic hair grooming is increasingly prevalent among men and women in the United States (Gaither et al., 2015;Herbenick, Schick, Reece, Sanders, & Fortenberry, 2010). There are numerous reasons to remove pubic hair; the most commonly reported are focused on sexual activity and sexual expression (Ramsey, Sweeney, Fraser, & Oades, 2009). Increasing access to sexually explicit material may also influence grooming motivation and trends (Vannier, Currie, & O'Sullivan, 2014). In a recent study, pubic hair grooming was strongly associated with sexual activity and practices (Gaither et al., 2015). Pubic hair grooming may lead to higher genital satisfaction and sexual function in women (Herbenick et al., 2010) and to greater positive body image in men . Interestingly, pubic hair-related grooming injuries have increased over the past 10 years, and it has been suggested that anogenital grooming may put one at risk for a sexually transmitted infection (STI; Gaither et al., 2015;Glass et al., 2012). The association between pubic hair grooming, sexual activity, and genital injuries/infections indicate that this is a potentially important but overlooked public health issue.
Baseline prevalence and characteristics of pubic hair grooming in women has been well studied. Among women, grooming is associated with younger ages, cunnilingus, and grooming-related genital injuries (DeMaria, Flores, Hirth, & Berenson, 2014;Herbenick et al., 2010;Herbenick et al., 2013). Very few studies have looked at baseline prevalence and characteristics of pubic hair grooming in men. A study of college students estimated the prevalence of below the neck grooming among men to be 63.6% (Boroughs, Cafri, & Thompson, 2005). The prevalence among men outside of college has not been studied. Given that grooming is associated with injuries and potentially STI, a more expansive study of pubic hair grooming in men is warranted.

Aims
The primary aim of the current study is to assess the prevalence and characteristics of pubic hair grooming in a national sample of U.S. men. The authors seek to understand the most common areas and methods men use for grooming, what demographic characteristics are associated with pubic hair grooming, and how pubic hair grooming is related to sexual activity. The authors hypothesize that grooming is more frequent in younger and more sexually active men. The intent of the current study is to provide information on common grooming practices to better inform clinicians who may be called to address issues of genital grooming in men.

Study Population
A nationally representative survey of noninstitutionalized adults aged 18 to 65 years residing in the United States was conducted. A questionnaire examining the prevalence of injuries and infections that occur as a result of personal grooming and associated risk factors was developed. The survey was conducted with the GfK Group (GfK, formerly Knowledge Networks). Details regarding GfK study methods have been reported previously ("Knowledge Panel Design Summary," 2013). The panel members are recruited using address-based sampling and random probability-based sampling to be representative of the population of the United States (Chang & Krosnick, 2009).
GfK samples addresses from the U.S. Postal Service's Delivery Sequence File. Address-based sampling estimates 97% of households can be reached and contacted through household mail (Chang & Krosnick, 2009). Once the panel members are recruited, they receive notification via e-mail to participate in a study sample. Panel members may also check their personal online member page to participate in survey taking. The topic of the survey is given to participants. Participants do not see any questions from a particular survey until they accept the survey. The topic of the current study given to participants was "Personal Grooming Injuries." GfK provides a laptop or netbook computer and free Internet service to all panel members without access to the Internet. For the current study, panel members received 1,000 points for completing the survey, which is the cash equivalent of $1.
In addition to standard measures taken by GfK to enhance survey cooperation, e-mail reminders were sent to nonresponders on Day 3 of the field period. Although the survey as a whole has not been validated elsewhere, a pretest survey was completed in December of 2013 to ensure participants understood the questions. The final survey was conducted in January of 2013 in which 7,580 subjects (men and women) completed the survey out of 14,409 sampled (completion rate of 52.5%). GfK consented all participants prior to the beginning of the survey.
GfK uses statistical weighting adjustments to correct for known deviations. Additional survey errors such as noncoverage and nonresponse are also corrected for using panel demographic poststratification weights. The Committee on Human Research at the first author's institution approved the study.

Predictor Variables
The survey instrument can be found in the appendix. The following demographic data were collected: age, race, relationship status, education, and geographic region. Baseline hairiness and genital satisfaction were collected using previously validated questionnaires (Davis, Paterson, & Binik, 2012;Ramsey et al., 2009) that use a 1 to 7 Likerttype scale. Sexual practice characteristics including sexual partner sex, sex frequency, number of sexual partners, and specific sexual behaviors was assessed.

Outcome Variables
Differences in characteristics between male groomers and nongroomers was explored. Groomers were defined as those respondents who reported regular grooming (daily, weekly, monthly, or yearly). Nongroomers were defined as those who never groomed their pubic hair or those who have groomed but did not report regular grooming (Question 5A in the appendix). The frequency, location, and method of removal were analyzed. Questions about personal grooming habits were asked including grooming frequency and intensity, such as how often the participant groomed all of his pubic hair. Instrument for pubic hair removal (e.g., razor, electrolysis, etc.), motivations for grooming (sex, trip to the doctor, etc.), and grooming locations (e.g., perineum, scrotum, etc.) were assessed.

Statistical Methods
Data analysis was conducted using the survey function in Stata v. 13.0 (Stata, StataCorp, College Station, TX, USA) to account for complex sampling design. Any p value less than .05 was considered statistically significant in univariate models and all statistical tests were two-sided. All missing or incomplete data were excluded from the analyses. Only data from men were included in the analysis. Demographic characteristics and sexual characteristics were compared between groomers and nongroomers using chi-square tests. Continuous variables were compared using a two-sided student's t test. All variables with a p value less than <.10 in univariate models as well as variables thought to be suggestive of grooming were added to the multivariate logistic model. Multivariate logistic regression was used to see which factors have the greatest odds of the outcome of grooming. Due to the large sample size and multiple tests in the multivariate model, Bonferroni adjustments were made to the alpha-level to prevent Type I errors.
Sexual characteristics of male groomers and nongroomers are reported in Table 2. Groomers report more lifetime sexual partners, compared with nongroomers (24.4 vs. 18.2, p = .01). A larger proportion of groomers reported having sex with men than the proportion of nongroomers (6.2% vs. 2.2%, p < .01). A larger proportion of groomers report daily sex compared with nongroomers (4.7% vs. 3.2, p < .01). Similar proportions of groomers  (1-7), genital satisfaction measured using the Index of Male Genital Image.
Results of the multivariable logistic regression for the outcome of grooming are reported in Table 3. The odds ratio (OR) for grooming with increasing age by 1 year was 0.95 (95% confidence interval [CI 0.94, 0.96]), p < .001. Men who report sexual activity 1 to 3 times per week have increased odds for grooming, OR = 1.49 (95% CI [1.20, 1.87]), compared with men who report sexual activity less than monthly. Men who reported performing oral genital sex and receiving oral genital sex compared with men who do not report those behaviors have increased odds for grooming, OR = 1.46 (95% CI [1.21, 1.75]) and OR = 1.48 (95% CI [1.22, 1.80]), respectively, with p < .001. There was no association of grooming with race or education level after adjusting for covariates.
Men report grooming their pubic hair for various reasons including sex and hygiene, comfort, and curiosity. Reasons for pubic hair grooming by age are reported in Figure 1. The majority of men report grooming in preparation for sexual activity with a peak prevalence of 73% among men aged 25 to 34 years. Less men report grooming for a trip to the doctor or for a surgical procedure with a peak prevalence of 18% among men aged 55 to 65 years. Other men report grooming due to comfort and/or appearance with a peak prevalence of 9% among men aged 45 to 54 years.
Areas where men groom their pubic hair are reported in Figure 2. The majority (91%) of groomers remove the hair above the penis. Scrotal grooming was more prevalent among men aged 34 to 44 years, with a peak prevalence of 72%. Removing inner thigh hair seems to decrease with age, with a prevalence of 45% in 18to 24-year-olds and a prevalence of 26% in 55-to 65-year-olds. Although less common, more than 10% of groomers in all age categories report grooming the hair around the anus. Twenty-four percent of groomers aged 25 to 34 years groom the area around the anus, and 11% of groomers aged 55 to 65 years groom the area around the anus.

Discussion
This is the first study to assess the prevalence and motivations of pubic hair grooming in a national, representative sample of U.S. men. Overall, pubic hair grooming in men is common. Grooming is more common in younger men. Certain sexual behaviors, especially receiving and giving oral sex, are associated with grooming. The top three motivations for grooming include sex, hygiene, and routine care. Most men who remove their pubic hair groom the hair above the penis, the scrotum, and the penile shaft. The prevalence of pubic hair grooming (50.5%) in men reported in the current study is similar to that reported by Boroughs et al. (2005;63.6%). Differences in these two estimates are likely due to different sample populations as well as the current study focused only on pubic hair grooming. Comparing the current results with work done in women, the authors demonstrate that the demographics and motivations for grooming are similar (Herbenick et al., 2010). Pubic hair removal in women is associated with younger ages, receiving cunnilingus, and a positive genital self-image (Herbenick et al., 2010). Grooming was associated with modestly higher genital satisfaction but this relationship did not persist after multivariable analysis. The prevalence of pubic hair grooming decreases with age (Table 1). Pubic hair growth in both men and women peaks in the mid-20s and later declines (Ayob & Messenger, 2015;Hamilton, 1958). Increased hair growth at these earlier ages may in part explain a greater prevalence of grooming in younger ages.
It is well documented that pubic hair grooming is associated with sexual activity and behavior (DeMaria & Berenson, 2013;Gaither et al., 2015;Herbenick et al., 2010;Herbenick et al., 2013;Ramsey et al., 2009;Tiggemann & Hodgson, 2008). The majority of studies to date have been in women or gay men. The current study identifies that the number one motivation for grooming among men of all ages was sex. Interestingly, in the multivariate model, higher frequency of sexual activity was not associated with greater odds of grooming. This suggests that, although men might groom for sex, other aspects of sexual behavior beyond frequency might influence grooming. In particular, oral sex seems to be associated with grooming in the current study as well as another study in women (Herbenick et al., 2010). Additional research on motivations for pubic hair removal prior to oral sex is warranted; likely explanations include partner preference/ease and or general hygiene concerns.
Muscularity, weight, height, and penis size are related to overall male body image . Grooming may play a role in male body image, as many college males report grooming for a drive of muscularity and physical appearance (Boroughs & Thompson, 2014). Perceived increase in physical appearance might be a reason that so many men groom for sex. Also, from Figure 1, about one in five men report  grooming because it makes their penis look longer, which may be another reason that so many men groom for sex. A common reason for grooming in women is concerns about perspiration and odor (Riddell, Varto, & Hodgson, 2010). The focus on hygiene as a reason to groom may be a male equivalent of this concern. Whether grooming actually decreases perspiration and odor has not been studied. Pubic hair grooming may also be a reflection of a religious hygienic teaching. For example, pubic hair shaving is recommended by the prophet Muhammad as part of an Islamic cleanliness teaching (Pfluger-Schindlbeck, 2006;Toerien & Wilkinson, 2004). Religious preferences were not captured by the current survey.
The strengths of this study include a large, nationally representative sample from a well-validated source. The external validity of the current study data is more robust than prior studies that have relied on convenience sampling in specific populations (Boroughs et al., 2005;Boroughs & Thompson, 2014;Martins et al., 2008). Participants completed the study via the Internet, which facilitates privacy and ease of access as the survey is of a sensitive nature. However, the current study is not without limitations. Although some questions have been previously validated, the survey as a whole has not been validated. Given the sensitive nature of the survey, some participants may not have felt comfortable answering questions about sexual behavior and pubic hair grooming, which may be a reflection of the lower response rate (52.5%). Despite these limitations, the authors do believe the findings of this study add to the further understanding of pubic hair grooming characteristics among men. Results of this study may allow clinicians, sex educators, and therapists to better counsel and understand patients with grooming concerns (Porche, 2007).

Conclusions
Pubic hair grooming is common among men aged 18 to 65 years in the United States. Younger ages are associated with a greater prevalence of pubic hair grooming. Many men groom for sex, in particular oral sex, as well as for routine care and hygiene.

Study Title: Pubic Hair Grooming Behaviors Among American Men and Women: A Study of Injuries Relating to Grooming Practices
Thank you for continuing to be part of the KnowledgePanel®.
This survey is being conducted by The University of California, San Francisco. .The study will help researchers understand more about pubic hair grooming behavior among men and women in the United States. About 7,500 people will participate in this study.

What Will Happen if I Take Part in This Study?
If you agree to be in this study, you will complete a survey online. It will take you about 5 to 10 minutes to complete the survey.
You will receive 1,000 points for completing this survey. (This is the cash equivalent of $1.) Are There Any Risks to Me or My Privacy? Some of the survey questions may make you feel uncomfortable or raise unpleasant memories. You are free to skip any question.
As with all KnowledgePanel surveys, your response to this survey, or any individual question in the survey, is completely voluntary. You will not be individually identified and your responses will be used for analyses only.
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If you have questions about your rights as a participant in this survey, or are dissatisfied at any time with any aspect of the survey, you may contact the KnowledgePanel Panel Member Support at 800-782-6899.
If you wish to speak directly to the investigator in charge of this study you can e-mail Dr. Benjamin Breyer, MD at BBreyer@urology.ucsf.edu.
If you wish to ask questions about the study or your rights as a research participant to someone other than the researchers or if you wish to voice any problems or concerns you may have about the study, please call the Office of the Committee on Human Research at 415-476-1814.
By Clicking the Next Button, You Are Giving Your Consent to Participate in the Study and Complete the Survey.

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This survey is aimed to gather information about pubic hair grooming behavior among [if ppgender=1 insert: men/if ppgender=2 insert: women]. We are particularly interested in understanding injuries related to pubic hair grooming and the situations in which these injuries may occur. All your responses are completely anonymous. Thank you for your honesty.
Please note that some questions in this survey contain drawings of genitalia, therefore we advise you take this survey in private. Q2a. Please select the image below which represents your ideal female hair pattern.

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Q2b. Please select the image below which represents your ideal male hair pattern.

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Q3. Have you ever removed or trimmed your pubic hair?

Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: NIH Grant K12DK083021 (BNB)