LONDON — Menopause is a natural aspect of aging for women, but there is no universal age when symptoms begin to appear. While most women typically enter menopause between the age of 45 and 55, it can happen later or earlier. The reasons behind these variations are believed to be numerous, ranging from genetic factors to lifestyle choices. Interestingly, researchers at University College London believe they have identified an additional factor that influences the onset of menopause: the frequency of sexual activity.

According to the study, women involved in monthly or weekly sexual activity are less likely to experience early menopause in comparison to women engaging in sexual activity less than once a month. Furthermore, women who reported being active sexually on a weekly basis were found to be 28% less likely to have experienced menopausal symptoms at any given age compared to women having sex less than monthly. Similarly, women having sex on a monthly basis were 19% less likely experience menopause at any given age than women only having sex sporadically (less than once per month).

For the purposes of this research, sexual activity was classified as intercourse, oral sex, sexual touching, and caressing / masturbation.

The research team came to these findings using data collected by the Study of Women’s Health Across the Nation (SWAN), the single largest, most diverse, and most comprehensive research effort that asked participants about their menopausal transition. The included data in this study encompassed 2,936 women, all of whom were recruited for the SWAN study in 1996 and 1997.

“The findings of our study suggest that if a woman is not having sex, and there is no chance of pregnancy, then the body ‘chooses’ not to invest in ovulation, as it would be pointless. There may be a biological energetic trade-off between investing energy into ovulation and investing elsewhere, such as keeping active by looking after grandchildren,” comments first study author and PhD candidate Megan Arnot in a release.

“The idea that women cease fertility in order to invest more time in their family is known as the Grandmother Hypothesis, which predicts that the menopause originally evolved in humans to reduce reproductive conflict between different generations of females, and allow women to increase their inclusive fitness through investing in their grandchildren,” she continues.

For the study, each woman was asked to answer a series of questions about their sex life, including how often they were having sex, the type of sexual activity, and masturbation habits. At least to start, most participants (64%) reported having sex on a weekly basis. At the beginning of the research period, none of the women had entered menopause, but 46% were entering peri-menopause (meaning they were beginning to experience very slight menopausal symptoms).

These interviews continued to be conducted over a 10 year period. During that time, 45% (1,324) of the women developed menopause, with the average age of development being 52.

Another finding of note: researchers tested to see if living with a male partner had any influence on age of menopausal onset, but found no such relationship.

“The menopause is, of course, an inevitability for women, and there is no behavioral intervention that will prevent reproductive cessation. Nonetheless, these results are an initial indication that menopause timing may be adaptive in response to the likelihood of becoming pregnant,” concludes study author & professor Ruth Mace.

The average age of participating women at the beginning of the interview period was 45. Caucasian women were the most represented group, making up 48% of the sample. Additionally, most of the participants had graduated from at least high school. The average participant had mothered two children, and most were married / in a relationship (78%) or living with a partner (68%).

The study is published in Royal Society Open Science.