New research suggests that women who engage in any sexual activity at least once a month tend to experience menopause later in life, compared with those who have sex less frequently.
A new study — the findings of which appear in the journal Royal Society Open Science — has aimed to find out whether the frequency of sexual activity has any bearing on when a woman enters menopause.
The researchers, Megan Arnot and Prof. Ruth Mace, from University College London, in the United Kingdom, did not just take penetrative sex into account. When referring to sexual activity, they also included oral sex, caressing, and masturbation.
The team analyzed data collected via the Study of Women’s Health Across the Nation (SWAN). The information came from 2,936 female participants who enrolled in SWAN in 1996 –1997 and whose collective mean age was 45 at their first interviews.
Most of the participants (48%) were non-Hispanic Caucasian and had more than a high school level of education. On average, each participant had two children. Most (78%) were either married or in a relationship and living with a romantic partner (68%).
In their interviews for the study, the participants described their health status and lifestyle, including how often they had engaged in sexual activity — with a partner or on their own — over the previous 6 months.
According to the data, most women (64%) reported engaging in some sort of sexual activity on a weekly basis.
At baseline, none of the SWAN participants had experienced menopause, though 46% had entered perimenopause, a stage at which menstruation is still occurring but some menopause symptoms, such as hot flashes, develop.
The researchers had access to follow-up interviews with the participants over a period of 10 years. During this time, 1,324 (45%) of the participants reported having entered menopause, at an average age of 52.
Arnot and Prof. Mace found that women who engaged in sexual activity on a weekly basis were less likely to experience early menopause than their peers who had sex less often than once a month.
Specifically, women of any age who engaged in sexual activity on a weekly basis appeared to have a hazard ratio of 0.72 when it came to experiencing early menopause. Those who engaged in sexual activity once a month had a 0.81 hazard ratio.
This means that women of any age who engaged in sex every week had a 28% lower likelihood of entering menopause early, compared with those who had some form of sex less frequently than once a month.
Women who engaged in sexual activity on a monthly basis had a 19% lower likelihood of experiencing early menopause than those who had sex less frequently.
These associations remained in place even after the researchers adjusted for confounding factors, such as a woman’s estrogen level, her level of education, body mass index, smoking habits, and the age at which she got her first period.
Arnot and Prof. Mace also investigated whether living with a male romantic partner might correlate in any way with menopause. This investigation was prompted by the possibility that closeness to male pheromones might delay menopause. However, the researchers found absolutely no evidence of this.
The question now is: What might explain an association between the frequency of sex and the age at which a woman enters menopause?
The researchers believe that it may have something to do with the level of energy that the body is ready to expend on ovulation, the mechanism that allows females to become pregnant.
“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,” says Arnot.
“There may be a biological energetic trade-off between investing energy into ovulation and investing it elsewhere, such as keeping active by looking after grandchildren,” she goes on to hypothesize.
The more a woman engages in some sort of sexual activity, the researchers explain, the more her body feels that there is a chance of pregnancy. But when the body has not engaged in sex recently, it is possible that pregnancy-related mechanisms begin to “turn off.”
This may have something to do with what some scientists call the “grandmother hypothesis.”
“The grandmother hypothesis […] predicts that 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,” Arnot explains.
There is another layer to this explanation. The researchers note that during ovulation the immune system functions less efficiently, leading to an increased likelihood of health problems.
This could mean that if the body senses that pregnancy is not in the cards — either because of prolonged sexual inactivity or high infrequency — it may automatically stop investing in ovulation, a very energy-costly process.
Menopause could thus help conserve energy that a woman could invest in other activities, such as looking after her next of kin — according to the grandmother hypothesis, at least.
“Menopause is, of course, an inevitability for women, and there is no behavioral intervention that will prevent reproductive cessation,” Prof. Mace emphasizes, commenting on the study’s findings. Still, she adds:
“Nonetheless, these results are an initial indication that menopause timing may be adaptive in response to the likelihood of becoming pregnant.”