European Journal of Obstetrics & Gynecology and Reproductive Biology 182 (2014) 118–122
Contents lists available at ScienceDirect
European Journal of Obstetrics & Gynecology and Reproductive Biology journal homepage: www.elsevier.com/locate/ejogrb
Orgasm and women’s waist circumference Rui Miguel Costa a, Stuart Brody b,* a b
ISPA—Instituto Universita´rio, Unidade de Investigac¸a˜o em Eco-Etologia (Eco-Ethology Research Unit), Lisbon, Portugal Charles University, Department of General Anthropology, Faculty of Humanities, Prague, Czech Republic
A R T I C L E I N F O
A B S T R A C T
Article history: Received 27 May 2014 Received in revised form 23 August 2014 Accepted 3 September 2014
Objective: Given that adiposity is related to poorer female sexual function, among many other health problems, the present study aimed at testing the hypothesis that larger waist circumference, an index of subcutaneous and abdominal fat mass, is associated with lack of specifically vaginal orgasm. Study design One hundred and twenty Portuguese women of reproductive age had their waist measured and reported their past month frequency of penile–vaginal intercourse (PVI), vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex (in the absence of same-day PVI), non-coital partnered sex orgasm (regardless of same-day PVI), masturbation, and masturbation orgasm. Results: In both simple and partial correlations (controlling for age, social desirability responding, relationship status, and cohabitation status), larger waist circumference was associated with lack of any vaginal orgasm and with having masturbated in the past month. In a multiple regression, larger waist circumference was independently predicted by lesser frequency of vaginal orgasm, greater frequency of masturbation, and older age. Conclusion: Abdominal fat mass appears to be adversely associated with lesser capacity for vaginal orgasm, but not for orgasms from other sexual activities. Results are discussed in the context of vaginal orgasm being relatively more contingent on situations of increased fitness in both partners. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Female orgasm Intercourse Waist circumference
Introduction Although the internal structures of the clitoris may have a role in sexual arousal before or during penile–vaginal intercourse (PVI), penile stimulation of the vagina is likely to create qualitatively different arousal and orgasms compared to stimulation focused on the clitoral glans. In addition to specific sensory qualities unique to PVI, there is evidence that (a) vaginal and cervical stimulation involves activation of different peripheral neurophysiological pathways and brain somatosensory cortex regions than clitoral stimulation [1]; (b) the likelihood of vaginal orgasm (attained by PVI without simultaneous clitoral masturbation) is associated with arousability from deep vaginal stimulation, but not with arousability from vulvar or clitoral stimulation [2]; and (c) vaginal and clitoral stimulation even produce functional differences at the root of clitoris [3]. Thus, the differences between vaginal orgasms and orgasms from other triggers involve physiological differences between internal stimulation by penis and by other forms of
* Corresponding author. E-mail address: [email protected] (S. Brody). http://dx.doi.org/10.1016/j.ejogrb.2014.09.007 0301-2115/ß 2014 Elsevier Ireland Ltd. All rights reserved.
stimulation. This differentiation is crucial, as vaginal orgasm is consistently associated with a host of indicators of better health and relationship quality, which is not the case for orgasms attained by non-coital sex or even by clitoral masturbation during PVI [4–6]. These findings led to the development of the theory that vaginal orgasm evolved to promote PVI and consequent gene transmission in situations of better fitness potential of the woman and/or her male partner(s) [7]. Accordingly, vaginal orgasm and the incentive to engage in PVI would be expected to be relatively more contingent upon the health of the woman and/or the male partner(s) than non-coital sex orgasm and the incentive to noncoital sex, which does not have the possibility of gene transmission. This theory is a more specific extension of the mate choice theory of female orgasm. Obesity and overweight are associated (independently of age) with impaired female sexual function [8–10], among many other physical and mental health problems [11,12]. Accordingly, adiposity is related to more orgasmic difficulties in women, as measured by the Female Sexual Function Index (FSFI) [8,9,13], a scale which unfortunately does not differentiate vaginal orgasm from other orgasm triggers. However, given that adiposity is associated with poorer physical and mental health [11,12], it is expected that
R.M. Costa, S. Brody / European Journal of Obstetrics & Gynecology and Reproductive Biology 182 (2014) 118–122
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excess weight contributes to lesser likelihood of vaginal orgasm, but not to difficulties in having orgasms by other means. Some empirical evidence suggests a link between slimness and greater frequency of PVI, but not other sexual activities: in a large nationally representative Czech sample, women’s slimmer waist was associated with greater PVI frequency, independently of age [14]; in a nonclinical sample of German women, larger hips were associated with lesser PVI frequency, but unrelated to frequency of non-coital partnered sex (in the absence of same day PVI) and of solitary masturbation [15]. Thus, the present study tests the hypothesis that greater vaginal orgasm frequency is associated with a smaller waist circumference, an important index of subcutaneous and abdominal fat mass.
satisfaction [5,17]. Thus, multiple regressions (using the backward exclusion method to provide a good balance of stability and statistical power) were conducted with waist circumference as the dependent variable, and the frequencies of the various orgasm triggers, age, social desirability responding, relationship status, and cohabitation, as independent variables. Regression entry threshold was p = 0.05 and removal threshold was p = 0.10. The sample size is adequate, given the expected effect size from a previous study showing that slimmer hips correlated with greater recalled PVI frequency in a sample of 59 women (r = 0.31, p = 0.002) [15]. The present sample of 120 women has an adequate power (>0.80) to detect an even smaller statistical effect of r = 0.25.
Materials and methods
Results
Participants
Sample characteristics
One hundred and forty-one women participated in a laboratory study after giving informed consent, and as part of the protocol, they reported their past month frequency of various sexual behaviors in anonymous and confidential questionnaires, and reported if they had a regular sexual partner, and if they were cohabiting with a sexual partner. At the conclusion of the session, waist circumference was measured at the level of the umbilicus with a metric tape by the experimenter or an assistant, both blind to sexual behavior reports. For the present study, only 120 women were included in the analyses, after exclusion of women who were breastfeeding (N =1), taking antidepressants (N = 10), in the menopause (N = 3), or not providing sexual behavior data (N = 10). One hundred and seventeen of the 120 were university students participating in the experiment in exchange for course credit, and three were unpaid volunteers from the community. The study was conducted in accordance with the ethical procedures of ISPA—Instituto Universita´rio (Lisbon, Portugal)—and complied with the Declaration of Helsinki (all participants were made aware of their right to discontinue participation at any time, and were made aware of the anonymity and confidentiality of their data).
Descriptive statistics for demographics and sexual behaviors are displayed in Tables 1 and 2, respectively.
Table 3 depicts simple linear correlations and partial correlations (controlling for age, social desirability responding, relationship status, and cohabitation status) between waist circumference and sexual behaviors. In both simple and partial correlations, having any past month occurrence of vaginal orgasm was associated with a slimmer waist. In contrast, having masturbated in the past month was associated with a larger waist. The mean waist circumference of participants who had any past month vaginal orgasm was 73.59 cm (SD = 8.64), in contrast to the 77.44 cm (SD = 10.32) mean waist of those participants who had no vaginal orgasm in that period (t = 2.22, p = 0.03). The mean waist circumference of participants who masturbated in the past month was 78.24 cm (SD = 10.11), in contrast to the 73.50 cm (SD = 8.54) of those who did not masturbate in that period (t = 2.71, p = 0.008).
Measures
Multiple regressions
Participants reported their past month frequency (days) of PVI, orgasm during PVI without direct clitoral stimulation, orgasm during PVI with direct clitoral stimulation, non-coital partnered sex (without same-day PVI), non-coital partnered sex orgasm (regardless of same-day PVI), masturbation, and masturbation orgasm [5]. The possibility of social desirability response bias was assessed with a 13-item short version of the Marlowe–Crowne Social Desirability Scale [16].
A multiple regression was performed predicting waist circumference from age, social desirability responding score, relationship status, cohabitation status, and past month frequencies of vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex orgasm, and masturbation. The independent predictors of waist circumference were lesser frequency of vaginal orgasm (b = 0.22, p = 0.01), greater masturbation frequency (b = 0.21, p = 0.02), and older age (b = 0.30, p = 0.001); multiple R = 0.41.
Correlations
Statistical analyses Simple linear and partial correlations controlling for age, relationship status, cohabitation status, and social desirability responding were used to examine the relationships between waist circumference and sexual behaviors. Because the frequency of some different partnered sexual behaviors tend to intercorrelate, sometimes their ultimate differential relationships with a given variable may become obscured by intercorrelations (such as those due to a non-coital activity being foreplay to PVI), unless multivariate analyses with several sexual behaviors as independent variables are used to disentangle the specific relationships [5,6,17–19]. This procedure has previously revealed a more consistent cross-cultural confirmation that PVI and vaginal orgasm are the sexual activities most consistently related to better health, better relationship satisfaction, and greater sexual
Table 1 Demographics (N = 120). Mean (SD) or % (N) Age (years) Waist circumference (cm) Involved in an ongoing relationship (%) Relationship duration (months)a Cohabiting (%) Sexuality best described as Only with the opposite sex (%) Mostly with the opposite sex (%) About equally with opposite and same sex (%) Mostly with same sex Only with same sex (%) SD = standard deviation a Relationship duration (months); median = 28.00
22.38 (6.51) 75.39 (9.62) 75.5 (87) 45.86 (61.93) 10.08 (13) 87.5 7.5 0.8 1.7 2.5
(105) (9) (1) (2) (3)
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Table 2 Descriptive statistics for sexual behaviors (N = 120).
PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital partnered sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm
Days in the past month Mean (SD)
Any in the past month % (N)
5.61 2.77 3.19 2.47 1.71 1.38 1.06
75 (90) 53.3 (64)a 57.5 (69) 52.5 (63) 44.5 (53) 35.3 (42) 31.1 (37)
(5.99) (4.23) (4.81) (3.96) (3.44) (2.69) (2.18)
SD = standard deviation a For the subsample with past month PVI, the prevalence of vaginal orgasm is 71.1%.
Another multiple regression was performed predicting waist circumference from age, social desirability responding score, relationship status, cohabitation status, and past month occurrence of any (versus no) vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex orgasm, and masturbation. The independent predictors of waist circumference were absence of vaginal orgasm (b = 0.18, p = 0.04), occurrence of masturbation (b = 0.19, p = 0.03), and older age (b = 0.27, p = 0.002); multiple R = 0.40.
Comments As hypothesized, a slimmer waist was associated with greater likelihood of having experienced vaginal orgasm in the preceding month (measured by number of days or dichotomously). In addition, a smaller waist was related to lesser likelihood of having masturbated in the same period (measured either by number of days or dichotomously). Age, relationship status, cohabitation status, and social desirability responding score did not confound the results. Masturbation frequency (in days) was not significantly correlated with waist circumference in the partial correlations controlling for such potential confounders, but became significant in multivariate analyses which additionally controlled for the various specific sexual behaviors. Although there was a non-significant trend for frequency of orgasm by clitoral masturbation during PVI being associated with a slimmer waist in partial correlations, there was no such trend in the regressions additionally controlling for other sexual behavior frequency. The multiple regression statistical procedure revealed independent associations of a larger waist
circumference with both less frequent vaginal orgasm and more frequent masturbation, providing evidence against the view that women with a larger waist tend to more masturbation simply because of lack of vaginal orgasm, PVI or otherwise partnered sexual activities. Once again, the procedure of multivariate analyses with various specific sexual behaviors as putative predictors demonstrated its utility in revealing the expected differential associations of sexual activities [5,6,17–19]. Because frequencies of vaginal orgasm and of orgasm from clitoral masturbation during PVI tend to correlate (because they both occur during PVI), it is important to use multivariate analyses to disentangle their differential associations. Other studies have demonstrated that multivariate analyses reveal more consistent differential associations of the two behaviors [5,18]. The observed pattern is consistent with other studies revealing that lesser masturbation frequency and greater PVI frequency are independently associated with greater satisfaction with several realms of life [17]. The findings were consistent with others showing that slimness is directly associated with PVI frequency [14,15], unrelated to frequency of partnered sexual activities in the absence of PVI in the same day [15], and inversely related to masturbation frequency [15]. In the latter study, however, the inverse association between masturbation and slimness was only obtained for men and for the total sample with both sexes combined. Interestingly, a recent study showed that the importance women attributed to junk food correlated directly with the importance they attributed to noncoital sex, but not with the importance attributed to PVI [20]. The present findings were also consistent with several others demonstrating that specifically vaginal orgasm is related to indices of better health [4–6], and are consistent with the theory that
Table 3 Simple linear correlations (model 1) and partial correlations (model 2; controlling for age, relationship status, cohabitation status, and social desirability responding) between waist circumference and sexual behaviors (N = 120). Waist circumference Model 1a r (p) Past month behavior frequency PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital partnered sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm Any past month behavior PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm
Waist circumference model 2b r (p)
S0.13 S0.16 S0.15 S0.04 S0.04 0.20 0.10
(0.16) (0.08) (0.10) (0.67) (0.68) (0.03) (0.26)
S0.15 S0.18 S0.16 0.02 0.01 0.17 0.05
(0.12) (0.05) (0.08) (0.80) (0.94) (0.07) (0.64)
S0.07 S0.20 S0.08 S0.03 S0.12 0.24 0.15
(0.46) (0.03) (0.39) (0.75) (0.19) (0.008) (0.10)
S0.13 S0.21 S0.13 0.06 S0.09 0.19 0.07
(0.17) (0.03) (0.17) (0.54) (0.32) (0.048) (0.46)
PVI = penile–vaginal intercourse a Simple linear correlations. b Partial correlations controlling for age, relationship status, cohabitation status, and social desirability responding.
R.M. Costa, S. Brody / European Journal of Obstetrics & Gynecology and Reproductive Biology 182 (2014) 118–122
vaginal orgasm might have evolved through natural selection to promote PVI under conditions propitious to increased fitness, encompassing woman’s physical and mental state, male partner characteristics, and relationship quality with the male partner [7]. This theory also provides an explanation of why vaginal orgasms might be somewhat more difficult to attain at a population level than clitoral orgasm. The findings were also congruent with others showing adverse correlates of masturbation [4]. Given that vaginal orgasm is more dependent (than are other women’s orgasms) upon men’s erectile potency and ability to prolong PVI [21,22], it is possible that the diminished physical attractiveness that adiposity normally brings sometimes had a negative impact on male sexual performance, and hence on male capacity to bring his female partner to vaginal orgasm. This view recently received empirical support from a study in a large nationally representative Czech sample showing that women’s larger waist predicted poorer erectile function in their partners, independently of age of self and age of partner [14]. Still consistent with this evolutionary view, it is also possible that women with less adiposity attract men with more fitness-related characteristics. Obesity might plausibly create some limitation in coital positions that could influence adversely the capacity for vaginal orgasm, but given the relatively low average waist circumference of the present sample, this latter explanation is not likely to explain the present results. In addition to evolutionary explanations for the findings, the link between adiposity and lack of vaginal orgasm might also be due at least in part to physiological mechanisms (an example being lower vagal tone [6]) or psychopathology. Related possibilities include that obesity might result from overeating with the purpose of diverting attention from unpleasant emotional states [23]; in this regard, it is noteworthy that lesser likelihood of vaginal orgasm is associated with greater use of immature psychological defence mechanisms [4,5], which indicates that women with lesser likelihood of vaginal orgasm have less effective ways to cope with stressors, and tend to cope by avoiding the awareness of emotions, including through emotional eating. Use of immature defence mechanisms is associated with a broad range of psychopathology [24]. Longitudinal studies found that the development of higher levels of adiposity were predicted by other indices of emotional dysregulation, such as anger, hostility, and depression [25], and by low conscientiousness [26]. The explanations provided herein for the relationship between vaginal orgasm and slimness are congruent with a longitudinal investigation which showed that higher body mass index was bi-directionally related to several types of health problems [27]. Curiously, it was found that clitoral size (body and crura) was larger in women with poorer sexual function and greater body mass index [28]. Future studies might examine the interrelationships between genital anatomy, sexual function, and adiposity. Strengths of the study include assessing a broad range of specific sexual behaviors and orgasmic responses, multivariate control for other sexual behaviors, and incorporating a measure of social desirability response bias. Limitations of the current study should be overcome by replicating the present study in larger and more representative samples, and incorporating measures of health, and partner and relationship characteristics to allowing the investigation of explanatory mechanisms and related interpersonal processes. Although lower adiposity might be more important than lower waist-hip ratio for women’s health and attractiveness (see [14] for a review), future research on female sexual behaviors and waist circumference might incorporate measurement of waist-to-hip ratio in addition to other health-related anthropometric measures of adiposity, such as hip circumference and body
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mass index. Given the association between vaginal orgasm and measures of better psychological and physiological health, as well as the finding that young women who are educated that their vagina is a source of their orgasm are indeed more likely to develop the capacity for vaginal orgasm [22], it is in the interest of women’s health, as well as science, to investigate the special role of vaginal orgasm [29]. Condensation Larger waist circumference is associated with lesser frequency of orgasm attained by penile–vaginal intercourse without concurrent clitoral masturbation (vaginal orgasm). Acknowledgment The study was supported with a grant from Fundac¸a˜o para a Cieˆncia e Tecnologia (FCT – DFRH – SFRH/BPD/76130/2011). References [1] Jannini EA, Rubio-Casillas A, Whipple B, Buisson O, Komisaruk BR, Brody S. Female orgasm(s): one, two, several. J Sex Med 2012;9:956–65. [2] Brody S, Klapilova K, Krejcova L. More frequent vaginal orgasm is associated with experiencing greater excitement from deep vaginal stimulation. J Sex Med 2013;10:1730–6. [3] Buisson O, Jannini EA. Pilot echographic study of the differences in clitoral involvement following clitoral or vaginal sexual Stimulation. J Sex Med 2013;10:2734–40. [4] Brody S. The relative health benefits of different sexual activities. J Sex Med 2010;7:1336–61. [5] Brody S, Costa RM. Vaginal orgasm is associated with less use of immature psychological defense mechanisms. J Sex Med 2008;5:1167–76. [6] Costa RM, Brody S. Greater resting heart rate variability is associated with orgasms through penile-vaginal intercourse, but not with orgasms from other sources. J Sex Med 2012;9:188–97. [7] Costa RM, Miller GF, Brody S. Women who prefer longer penises are more likely to have vaginal orgasms (but not clitoral orgasms): implications for an evolutionary theory of vaginal orgasm. J Sex Med 2012;9:3079–88. [8] Esposito K, Ciotola M, Giugliano F, et al. Association of body weight with sexual function in women. Int J Impot Res 2007;19:353–7. [9] Castellini G, Mannucci E, Mazzei C, et al. Sexual function in obese women with and without binge eating disorder. J Sex Med 2010;7:3969–78. [10] Zueff LN, da Silva Lara LA, Vieira CS, Martins WP, Ferriani RA. Body composition characteristics predict sexual functioning in obese women with or without PCOS. J Sex Marital Ther 2013. http://dx.doi.org/10.1080/0092623X. 864369. [11] Mason C, Craig CL, Katzmarzyk PT. Influence of central and extremity circumferences on all-cause mortality in men and women. Obesity (Silver Spring) 2008;16:2690–5. [12] McCrea RL, Berger YG, King MB. Body mass index and common mental disorders: exploring the shape of the association and its moderation by age, gender and education. Int J Obes (Lond) 2012;36:414–21. [13] Yaylali GF, Tekekoglu S, Akin F. Sexual dysfunction in obese and overweight women. Int J Impot Res 2010;22:220–6. [14] Brody S, Weiss P. Slimmer women’s waist is associated with better erectile function in men independent of age. Arch Sex Behav 2013;42:1191–8. [15] Brody S. Slimness is associated with greater intercourse and lesser masturbation frequency. J Sex Marital Ther 2004;30:251–61. [16] Ballard R. Short forms of the Marlowe-Crowne social desirability scale. Psychol Rep 1992;71:1155–60. [17] Brody S, Costa RM. Satisfaction (sexual, life, relationship, and mental health) is associated directly with penile-vaginal intercourse but inversely with other sexual behavior frequencies. J Sex Med 2009;6:1947–54. [18] Costa RM, Brody S. Anxious and avoidant attachment, vibrator use, anal sex, and impaired vaginal orgasm. J Sex Med 2011;8:2493–500. [19] Philippsohn S, Hartmann U. Determinants of sexual satisfaction in a sample of German women. J Sex Med 2009;6:1001–10. [20] Costa RM, Brody S. Immature psychological defense mechanisms are associated with greater personal importance of junk food, alcohol, and television. Psychiatry Res 2013;30:535–9. [21] Weiss P, Brody S. International Index of Erectile Function (IIEF) scores generated by men or female partners correlate equally well with own satisfaction (sexual, partnership, life, and mental health). J Sex Med 2011;8:1404–10. [22] Brody S, Weiss P. Vaginal orgasm is associated with vaginal (not clitoral) sex education, focusing mental attention on vaginal sensations, intercourse duration, and a preference for a longer penis. J Sex Med 2010;7:2774–81. [23] Strien TV, Peter Herman C, Verheijden MW. Eating style, overeating and weight gain: a prospective 2-year follow-up study in a representative Dutch sample. Appetite 2012;59:782–9.
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[24] Bond M. Empirical studies of defense style: relationships with psychopathology and change. Harv Rev Psychiatry 2004;12:263–78. [25] Goldbacher EM, Matthews KA. Are psychological characteristics related to risk of the metabolic syndrome? A review of the literature. Ann Behav Med 2007;34:240–52. [26] Terracciano A, Sutin AR, McCrae RR, et al. Facets of personality linked to underweight and overweight. Psychosom Med 2009;71:682–9.
[27] Cameron AJ, Magliano DJ, Dunstan DW, et al. A bi-directional relationship between obesity and health-related quality of life: evidence from the longitudinal AusDiab study. Int J Obes (Lond) 2012;36:295–303. [28] Vaccaro CM, Fellner AN, Pauls RN. Female sexual function and the clitoral complex using pelvic MRI assessment. Eur J Obstet Gynecol Reprod Biol 2014;180:180–5. [29] Brody S, Costa RM, Hess U. ‘‘Standard operating procedures for female orgasmic disorder’’ is not based on best evidence. J Sex Med 2013;10:2606–9.
Contents lists available at ScienceDirect
European Journal of Obstetrics & Gynecology and Reproductive Biology journal homepage: www.elsevier.com/locate/ejogrb
Orgasm and women’s waist circumference Rui Miguel Costa a, Stuart Brody b,* a b
ISPA—Instituto Universita´rio, Unidade de Investigac¸a˜o em Eco-Etologia (Eco-Ethology Research Unit), Lisbon, Portugal Charles University, Department of General Anthropology, Faculty of Humanities, Prague, Czech Republic
A R T I C L E I N F O
A B S T R A C T
Article history: Received 27 May 2014 Received in revised form 23 August 2014 Accepted 3 September 2014
Objective: Given that adiposity is related to poorer female sexual function, among many other health problems, the present study aimed at testing the hypothesis that larger waist circumference, an index of subcutaneous and abdominal fat mass, is associated with lack of specifically vaginal orgasm. Study design One hundred and twenty Portuguese women of reproductive age had their waist measured and reported their past month frequency of penile–vaginal intercourse (PVI), vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex (in the absence of same-day PVI), non-coital partnered sex orgasm (regardless of same-day PVI), masturbation, and masturbation orgasm. Results: In both simple and partial correlations (controlling for age, social desirability responding, relationship status, and cohabitation status), larger waist circumference was associated with lack of any vaginal orgasm and with having masturbated in the past month. In a multiple regression, larger waist circumference was independently predicted by lesser frequency of vaginal orgasm, greater frequency of masturbation, and older age. Conclusion: Abdominal fat mass appears to be adversely associated with lesser capacity for vaginal orgasm, but not for orgasms from other sexual activities. Results are discussed in the context of vaginal orgasm being relatively more contingent on situations of increased fitness in both partners. ß 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: Female orgasm Intercourse Waist circumference
Introduction Although the internal structures of the clitoris may have a role in sexual arousal before or during penile–vaginal intercourse (PVI), penile stimulation of the vagina is likely to create qualitatively different arousal and orgasms compared to stimulation focused on the clitoral glans. In addition to specific sensory qualities unique to PVI, there is evidence that (a) vaginal and cervical stimulation involves activation of different peripheral neurophysiological pathways and brain somatosensory cortex regions than clitoral stimulation [1]; (b) the likelihood of vaginal orgasm (attained by PVI without simultaneous clitoral masturbation) is associated with arousability from deep vaginal stimulation, but not with arousability from vulvar or clitoral stimulation [2]; and (c) vaginal and clitoral stimulation even produce functional differences at the root of clitoris [3]. Thus, the differences between vaginal orgasms and orgasms from other triggers involve physiological differences between internal stimulation by penis and by other forms of
* Corresponding author. E-mail address: [email protected] (S. Brody). http://dx.doi.org/10.1016/j.ejogrb.2014.09.007 0301-2115/ß 2014 Elsevier Ireland Ltd. All rights reserved.
stimulation. This differentiation is crucial, as vaginal orgasm is consistently associated with a host of indicators of better health and relationship quality, which is not the case for orgasms attained by non-coital sex or even by clitoral masturbation during PVI [4–6]. These findings led to the development of the theory that vaginal orgasm evolved to promote PVI and consequent gene transmission in situations of better fitness potential of the woman and/or her male partner(s) [7]. Accordingly, vaginal orgasm and the incentive to engage in PVI would be expected to be relatively more contingent upon the health of the woman and/or the male partner(s) than non-coital sex orgasm and the incentive to noncoital sex, which does not have the possibility of gene transmission. This theory is a more specific extension of the mate choice theory of female orgasm. Obesity and overweight are associated (independently of age) with impaired female sexual function [8–10], among many other physical and mental health problems [11,12]. Accordingly, adiposity is related to more orgasmic difficulties in women, as measured by the Female Sexual Function Index (FSFI) [8,9,13], a scale which unfortunately does not differentiate vaginal orgasm from other orgasm triggers. However, given that adiposity is associated with poorer physical and mental health [11,12], it is expected that
R.M. Costa, S. Brody / European Journal of Obstetrics & Gynecology and Reproductive Biology 182 (2014) 118–122
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excess weight contributes to lesser likelihood of vaginal orgasm, but not to difficulties in having orgasms by other means. Some empirical evidence suggests a link between slimness and greater frequency of PVI, but not other sexual activities: in a large nationally representative Czech sample, women’s slimmer waist was associated with greater PVI frequency, independently of age [14]; in a nonclinical sample of German women, larger hips were associated with lesser PVI frequency, but unrelated to frequency of non-coital partnered sex (in the absence of same day PVI) and of solitary masturbation [15]. Thus, the present study tests the hypothesis that greater vaginal orgasm frequency is associated with a smaller waist circumference, an important index of subcutaneous and abdominal fat mass.
satisfaction [5,17]. Thus, multiple regressions (using the backward exclusion method to provide a good balance of stability and statistical power) were conducted with waist circumference as the dependent variable, and the frequencies of the various orgasm triggers, age, social desirability responding, relationship status, and cohabitation, as independent variables. Regression entry threshold was p = 0.05 and removal threshold was p = 0.10. The sample size is adequate, given the expected effect size from a previous study showing that slimmer hips correlated with greater recalled PVI frequency in a sample of 59 women (r = 0.31, p = 0.002) [15]. The present sample of 120 women has an adequate power (>0.80) to detect an even smaller statistical effect of r = 0.25.
Materials and methods
Results
Participants
Sample characteristics
One hundred and forty-one women participated in a laboratory study after giving informed consent, and as part of the protocol, they reported their past month frequency of various sexual behaviors in anonymous and confidential questionnaires, and reported if they had a regular sexual partner, and if they were cohabiting with a sexual partner. At the conclusion of the session, waist circumference was measured at the level of the umbilicus with a metric tape by the experimenter or an assistant, both blind to sexual behavior reports. For the present study, only 120 women were included in the analyses, after exclusion of women who were breastfeeding (N =1), taking antidepressants (N = 10), in the menopause (N = 3), or not providing sexual behavior data (N = 10). One hundred and seventeen of the 120 were university students participating in the experiment in exchange for course credit, and three were unpaid volunteers from the community. The study was conducted in accordance with the ethical procedures of ISPA—Instituto Universita´rio (Lisbon, Portugal)—and complied with the Declaration of Helsinki (all participants were made aware of their right to discontinue participation at any time, and were made aware of the anonymity and confidentiality of their data).
Descriptive statistics for demographics and sexual behaviors are displayed in Tables 1 and 2, respectively.
Table 3 depicts simple linear correlations and partial correlations (controlling for age, social desirability responding, relationship status, and cohabitation status) between waist circumference and sexual behaviors. In both simple and partial correlations, having any past month occurrence of vaginal orgasm was associated with a slimmer waist. In contrast, having masturbated in the past month was associated with a larger waist. The mean waist circumference of participants who had any past month vaginal orgasm was 73.59 cm (SD = 8.64), in contrast to the 77.44 cm (SD = 10.32) mean waist of those participants who had no vaginal orgasm in that period (t = 2.22, p = 0.03). The mean waist circumference of participants who masturbated in the past month was 78.24 cm (SD = 10.11), in contrast to the 73.50 cm (SD = 8.54) of those who did not masturbate in that period (t = 2.71, p = 0.008).
Measures
Multiple regressions
Participants reported their past month frequency (days) of PVI, orgasm during PVI without direct clitoral stimulation, orgasm during PVI with direct clitoral stimulation, non-coital partnered sex (without same-day PVI), non-coital partnered sex orgasm (regardless of same-day PVI), masturbation, and masturbation orgasm [5]. The possibility of social desirability response bias was assessed with a 13-item short version of the Marlowe–Crowne Social Desirability Scale [16].
A multiple regression was performed predicting waist circumference from age, social desirability responding score, relationship status, cohabitation status, and past month frequencies of vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex orgasm, and masturbation. The independent predictors of waist circumference were lesser frequency of vaginal orgasm (b = 0.22, p = 0.01), greater masturbation frequency (b = 0.21, p = 0.02), and older age (b = 0.30, p = 0.001); multiple R = 0.41.
Correlations
Statistical analyses Simple linear and partial correlations controlling for age, relationship status, cohabitation status, and social desirability responding were used to examine the relationships between waist circumference and sexual behaviors. Because the frequency of some different partnered sexual behaviors tend to intercorrelate, sometimes their ultimate differential relationships with a given variable may become obscured by intercorrelations (such as those due to a non-coital activity being foreplay to PVI), unless multivariate analyses with several sexual behaviors as independent variables are used to disentangle the specific relationships [5,6,17–19]. This procedure has previously revealed a more consistent cross-cultural confirmation that PVI and vaginal orgasm are the sexual activities most consistently related to better health, better relationship satisfaction, and greater sexual
Table 1 Demographics (N = 120). Mean (SD) or % (N) Age (years) Waist circumference (cm) Involved in an ongoing relationship (%) Relationship duration (months)a Cohabiting (%) Sexuality best described as Only with the opposite sex (%) Mostly with the opposite sex (%) About equally with opposite and same sex (%) Mostly with same sex Only with same sex (%) SD = standard deviation a Relationship duration (months); median = 28.00
22.38 (6.51) 75.39 (9.62) 75.5 (87) 45.86 (61.93) 10.08 (13) 87.5 7.5 0.8 1.7 2.5
(105) (9) (1) (2) (3)
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Table 2 Descriptive statistics for sexual behaviors (N = 120).
PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital partnered sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm
Days in the past month Mean (SD)
Any in the past month % (N)
5.61 2.77 3.19 2.47 1.71 1.38 1.06
75 (90) 53.3 (64)a 57.5 (69) 52.5 (63) 44.5 (53) 35.3 (42) 31.1 (37)
(5.99) (4.23) (4.81) (3.96) (3.44) (2.69) (2.18)
SD = standard deviation a For the subsample with past month PVI, the prevalence of vaginal orgasm is 71.1%.
Another multiple regression was performed predicting waist circumference from age, social desirability responding score, relationship status, cohabitation status, and past month occurrence of any (versus no) vaginal orgasm, orgasm from clitoral masturbation during PVI, non-coital partnered sex orgasm, and masturbation. The independent predictors of waist circumference were absence of vaginal orgasm (b = 0.18, p = 0.04), occurrence of masturbation (b = 0.19, p = 0.03), and older age (b = 0.27, p = 0.002); multiple R = 0.40.
Comments As hypothesized, a slimmer waist was associated with greater likelihood of having experienced vaginal orgasm in the preceding month (measured by number of days or dichotomously). In addition, a smaller waist was related to lesser likelihood of having masturbated in the same period (measured either by number of days or dichotomously). Age, relationship status, cohabitation status, and social desirability responding score did not confound the results. Masturbation frequency (in days) was not significantly correlated with waist circumference in the partial correlations controlling for such potential confounders, but became significant in multivariate analyses which additionally controlled for the various specific sexual behaviors. Although there was a non-significant trend for frequency of orgasm by clitoral masturbation during PVI being associated with a slimmer waist in partial correlations, there was no such trend in the regressions additionally controlling for other sexual behavior frequency. The multiple regression statistical procedure revealed independent associations of a larger waist
circumference with both less frequent vaginal orgasm and more frequent masturbation, providing evidence against the view that women with a larger waist tend to more masturbation simply because of lack of vaginal orgasm, PVI or otherwise partnered sexual activities. Once again, the procedure of multivariate analyses with various specific sexual behaviors as putative predictors demonstrated its utility in revealing the expected differential associations of sexual activities [5,6,17–19]. Because frequencies of vaginal orgasm and of orgasm from clitoral masturbation during PVI tend to correlate (because they both occur during PVI), it is important to use multivariate analyses to disentangle their differential associations. Other studies have demonstrated that multivariate analyses reveal more consistent differential associations of the two behaviors [5,18]. The observed pattern is consistent with other studies revealing that lesser masturbation frequency and greater PVI frequency are independently associated with greater satisfaction with several realms of life [17]. The findings were consistent with others showing that slimness is directly associated with PVI frequency [14,15], unrelated to frequency of partnered sexual activities in the absence of PVI in the same day [15], and inversely related to masturbation frequency [15]. In the latter study, however, the inverse association between masturbation and slimness was only obtained for men and for the total sample with both sexes combined. Interestingly, a recent study showed that the importance women attributed to junk food correlated directly with the importance they attributed to noncoital sex, but not with the importance attributed to PVI [20]. The present findings were also consistent with several others demonstrating that specifically vaginal orgasm is related to indices of better health [4–6], and are consistent with the theory that
Table 3 Simple linear correlations (model 1) and partial correlations (model 2; controlling for age, relationship status, cohabitation status, and social desirability responding) between waist circumference and sexual behaviors (N = 120). Waist circumference Model 1a r (p) Past month behavior frequency PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital partnered sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm Any past month behavior PVI Vaginal orgasm Orgasm from clitoral masturbation during PVI Noncoital sex (without same day PVI) Noncoital partnered sex orgasm (regardless of same day PVI) Masturbation Masturbation orgasm
Waist circumference model 2b r (p)
S0.13 S0.16 S0.15 S0.04 S0.04 0.20 0.10
(0.16) (0.08) (0.10) (0.67) (0.68) (0.03) (0.26)
S0.15 S0.18 S0.16 0.02 0.01 0.17 0.05
(0.12) (0.05) (0.08) (0.80) (0.94) (0.07) (0.64)
S0.07 S0.20 S0.08 S0.03 S0.12 0.24 0.15
(0.46) (0.03) (0.39) (0.75) (0.19) (0.008) (0.10)
S0.13 S0.21 S0.13 0.06 S0.09 0.19 0.07
(0.17) (0.03) (0.17) (0.54) (0.32) (0.048) (0.46)
PVI = penile–vaginal intercourse a Simple linear correlations. b Partial correlations controlling for age, relationship status, cohabitation status, and social desirability responding.
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vaginal orgasm might have evolved through natural selection to promote PVI under conditions propitious to increased fitness, encompassing woman’s physical and mental state, male partner characteristics, and relationship quality with the male partner [7]. This theory also provides an explanation of why vaginal orgasms might be somewhat more difficult to attain at a population level than clitoral orgasm. The findings were also congruent with others showing adverse correlates of masturbation [4]. Given that vaginal orgasm is more dependent (than are other women’s orgasms) upon men’s erectile potency and ability to prolong PVI [21,22], it is possible that the diminished physical attractiveness that adiposity normally brings sometimes had a negative impact on male sexual performance, and hence on male capacity to bring his female partner to vaginal orgasm. This view recently received empirical support from a study in a large nationally representative Czech sample showing that women’s larger waist predicted poorer erectile function in their partners, independently of age of self and age of partner [14]. Still consistent with this evolutionary view, it is also possible that women with less adiposity attract men with more fitness-related characteristics. Obesity might plausibly create some limitation in coital positions that could influence adversely the capacity for vaginal orgasm, but given the relatively low average waist circumference of the present sample, this latter explanation is not likely to explain the present results. In addition to evolutionary explanations for the findings, the link between adiposity and lack of vaginal orgasm might also be due at least in part to physiological mechanisms (an example being lower vagal tone [6]) or psychopathology. Related possibilities include that obesity might result from overeating with the purpose of diverting attention from unpleasant emotional states [23]; in this regard, it is noteworthy that lesser likelihood of vaginal orgasm is associated with greater use of immature psychological defence mechanisms [4,5], which indicates that women with lesser likelihood of vaginal orgasm have less effective ways to cope with stressors, and tend to cope by avoiding the awareness of emotions, including through emotional eating. Use of immature defence mechanisms is associated with a broad range of psychopathology [24]. Longitudinal studies found that the development of higher levels of adiposity were predicted by other indices of emotional dysregulation, such as anger, hostility, and depression [25], and by low conscientiousness [26]. The explanations provided herein for the relationship between vaginal orgasm and slimness are congruent with a longitudinal investigation which showed that higher body mass index was bi-directionally related to several types of health problems [27]. Curiously, it was found that clitoral size (body and crura) was larger in women with poorer sexual function and greater body mass index [28]. Future studies might examine the interrelationships between genital anatomy, sexual function, and adiposity. Strengths of the study include assessing a broad range of specific sexual behaviors and orgasmic responses, multivariate control for other sexual behaviors, and incorporating a measure of social desirability response bias. Limitations of the current study should be overcome by replicating the present study in larger and more representative samples, and incorporating measures of health, and partner and relationship characteristics to allowing the investigation of explanatory mechanisms and related interpersonal processes. Although lower adiposity might be more important than lower waist-hip ratio for women’s health and attractiveness (see [14] for a review), future research on female sexual behaviors and waist circumference might incorporate measurement of waist-to-hip ratio in addition to other health-related anthropometric measures of adiposity, such as hip circumference and body
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mass index. Given the association between vaginal orgasm and measures of better psychological and physiological health, as well as the finding that young women who are educated that their vagina is a source of their orgasm are indeed more likely to develop the capacity for vaginal orgasm [22], it is in the interest of women’s health, as well as science, to investigate the special role of vaginal orgasm [29]. Condensation Larger waist circumference is associated with lesser frequency of orgasm attained by penile–vaginal intercourse without concurrent clitoral masturbation (vaginal orgasm). Acknowledgment The study was supported with a grant from Fundac¸a˜o para a Cieˆncia e Tecnologia (FCT – DFRH – SFRH/BPD/76130/2011). References [1] Jannini EA, Rubio-Casillas A, Whipple B, Buisson O, Komisaruk BR, Brody S. Female orgasm(s): one, two, several. J Sex Med 2012;9:956–65. [2] Brody S, Klapilova K, Krejcova L. More frequent vaginal orgasm is associated with experiencing greater excitement from deep vaginal stimulation. J Sex Med 2013;10:1730–6. [3] Buisson O, Jannini EA. Pilot echographic study of the differences in clitoral involvement following clitoral or vaginal sexual Stimulation. J Sex Med 2013;10:2734–40. [4] Brody S. The relative health benefits of different sexual activities. J Sex Med 2010;7:1336–61. [5] Brody S, Costa RM. Vaginal orgasm is associated with less use of immature psychological defense mechanisms. J Sex Med 2008;5:1167–76. [6] Costa RM, Brody S. Greater resting heart rate variability is associated with orgasms through penile-vaginal intercourse, but not with orgasms from other sources. J Sex Med 2012;9:188–97. [7] Costa RM, Miller GF, Brody S. Women who prefer longer penises are more likely to have vaginal orgasms (but not clitoral orgasms): implications for an evolutionary theory of vaginal orgasm. J Sex Med 2012;9:3079–88. [8] Esposito K, Ciotola M, Giugliano F, et al. Association of body weight with sexual function in women. Int J Impot Res 2007;19:353–7. [9] Castellini G, Mannucci E, Mazzei C, et al. Sexual function in obese women with and without binge eating disorder. J Sex Med 2010;7:3969–78. [10] Zueff LN, da Silva Lara LA, Vieira CS, Martins WP, Ferriani RA. Body composition characteristics predict sexual functioning in obese women with or without PCOS. J Sex Marital Ther 2013. http://dx.doi.org/10.1080/0092623X. 864369. [11] Mason C, Craig CL, Katzmarzyk PT. Influence of central and extremity circumferences on all-cause mortality in men and women. Obesity (Silver Spring) 2008;16:2690–5. [12] McCrea RL, Berger YG, King MB. Body mass index and common mental disorders: exploring the shape of the association and its moderation by age, gender and education. Int J Obes (Lond) 2012;36:414–21. [13] Yaylali GF, Tekekoglu S, Akin F. Sexual dysfunction in obese and overweight women. Int J Impot Res 2010;22:220–6. [14] Brody S, Weiss P. Slimmer women’s waist is associated with better erectile function in men independent of age. Arch Sex Behav 2013;42:1191–8. [15] Brody S. Slimness is associated with greater intercourse and lesser masturbation frequency. J Sex Marital Ther 2004;30:251–61. [16] Ballard R. Short forms of the Marlowe-Crowne social desirability scale. Psychol Rep 1992;71:1155–60. [17] Brody S, Costa RM. Satisfaction (sexual, life, relationship, and mental health) is associated directly with penile-vaginal intercourse but inversely with other sexual behavior frequencies. J Sex Med 2009;6:1947–54. [18] Costa RM, Brody S. Anxious and avoidant attachment, vibrator use, anal sex, and impaired vaginal orgasm. J Sex Med 2011;8:2493–500. [19] Philippsohn S, Hartmann U. Determinants of sexual satisfaction in a sample of German women. J Sex Med 2009;6:1001–10. [20] Costa RM, Brody S. Immature psychological defense mechanisms are associated with greater personal importance of junk food, alcohol, and television. Psychiatry Res 2013;30:535–9. [21] Weiss P, Brody S. International Index of Erectile Function (IIEF) scores generated by men or female partners correlate equally well with own satisfaction (sexual, partnership, life, and mental health). J Sex Med 2011;8:1404–10. [22] Brody S, Weiss P. Vaginal orgasm is associated with vaginal (not clitoral) sex education, focusing mental attention on vaginal sensations, intercourse duration, and a preference for a longer penis. J Sex Med 2010;7:2774–81. [23] Strien TV, Peter Herman C, Verheijden MW. Eating style, overeating and weight gain: a prospective 2-year follow-up study in a representative Dutch sample. Appetite 2012;59:782–9.
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[27] Cameron AJ, Magliano DJ, Dunstan DW, et al. A bi-directional relationship between obesity and health-related quality of life: evidence from the longitudinal AusDiab study. Int J Obes (Lond) 2012;36:295–303. [28] Vaccaro CM, Fellner AN, Pauls RN. Female sexual function and the clitoral complex using pelvic MRI assessment. Eur J Obstet Gynecol Reprod Biol 2014;180:180–5. [29] Brody S, Costa RM, Hess U. ‘‘Standard operating procedures for female orgasmic disorder’’ is not based on best evidence. J Sex Med 2013;10:2606–9.
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