Women with wide hips have been the object of desire for men since the beginning of time, as evolutionary psychology suggests, because wide hips are ideal for childbirth. The attraction to “child-bearing hips” stems from the belief that those with this figure are healthy and fertile, therefore making them desirable candidates for mating. Now, according to a recent study published in the Archives of Sexual Behavior, women with wide hips are likely to have more sexual partners and one-night stands, not because men find them more attractive, but because they feel more in control of their own sexual behavior and find childbirth less traumatic.

“Women's hip width has a direct impact on their risk of potentially fatal childbirth-related injury,” said Colin Hendrie, lead author of the study and associate professor of Human and Animal Ethology at Leeds University, in the news release. Waist-to-hip ratio has always been an important display of fertility as evolution designed female hips to become just wide enough to accommodate the demands of both reproduction and locomotion. Infants are born at a less developed stage than most other primates because of this restriction. Hendrie and his colleagues believe this very easiness of childbirth for wide-hipped women could lead them to engage in riskier sexual behavior.

To investigate whether hip width has a significant influence on a woman’s sexual behavior, the team of British researchers from Leeds University recruited a cohort of 148 women between the ages of 18 and 26. The female participants had their hip circumference at the widest point measured and their waist circumference at its narrowest point. In the study, wide hips were defined as those wider than 14.2 inches and small hips as those under 12.2 inches. This is measured by the distance between the upper outer edges of the iliac crest bones of the pelvis.

Questionnaires were administered to the participants asking about their sexual histories, including the age at which they lost their virginity, the number of sexual partners they’d had, and information about emotionally significant sexual relationships they had. All of the participants had at least one sexual partner previously. The average age of virginity being lost was 16, and in extreme cases, some women admitted to having a couple of hundred sexual partners.

The findings revealed women who were more likely to have one-night stands had wider hips. For these women whose one-night stands accounted for three out of every four of their sexual relationships, they had at least 0.8-inch wider hips than those who had less one-night stands. As a whole, the participants with hips wider than 12.4 inches had more sexual partners and more one-night stands than women with hips under 12.2 inches.

The study highlights that when women have control over their own sexual activity, this risk is seen in their behavior. Hendrie concludes: “Women’s sexual activity is therefore at least in part influenced by hip width.” As a result, a woman’s body shape plays an important role in her decision to have sex, with childbirth also influencing sexual behavior.

The researchers also suggest women with smaller hips tend to err on the side of caution when it comes to sex — driven by the fear of maternal mortality/risk of gynecological injury. “We found that women with smaller hips tended to have, throughout their entire sexual histories, just a couple of sexual partners. They really only had sex with people in the context of relationships, demonstrating a more cautious sexual strategy. If they got pregnant there would be someone in their life to help them,” Hendrie said, The Telegraph reported. Hendrie notes it remains to be seen if these conclusions can be generalized to other populations and cultures.

Source: Brewer G, Hendrie CA, Simpson VJ. Evidence to Suggest that Women’s Sexual Behavior is Influenced by Hip Width Rather than Waist-to-Hip Ratio. Archives of Sexual Behavior. 2014.