 The age of menopause is only partly determined by genetics, so what about the influence of lifestyle factors? Watch the video to find out. Since 1970, the proportion of women having their first child after age 35 increased nearly tenfold. This may introduce a longevity penalty on their children as those born to older mothers don't tend to live as long. But mothers having children later tend to live longer themselves. For example, female centenarians were found to be nearly four times more likely to have had children after age 40 than women who died by their 70s. This doesn't necessarily mean delaying kids will make you live longer. Smoking, for example, could be a confounder, causing both early menopause and an early death. Or maybe delayed reproductive aging is just a sign of slower aging in general. However, some have suggested the biological changes of pregnancy might have a rejuvenating effect, even going so far as to suggest a parabiosis mechanism bathing in the blood of babies, but just not an accountus bathery sort of way. To sort between these possibilities, researchers studied the longevity of brothers of women who gave birth after age 45 and that of their wives. The brothers with late fertile sisters lived longer, but their wives did not. This suggests a genetic robustness cause, rather than a rejuvenation effect. And the fact that the longevity benefit didn't extend to their wives suggests it's not due to a confounder like socioeconomic strata. On the other hand, women who experience extremely early menopause, the one percent who stopped menstruating by age 39, may be at risk for diminished longevity, and should therefore be counseled to adopt a particularly healthy diet and lifestyle. Approximately half of the variability of age of menopause between women is explained by genetics. Other than smoking, what other behaviors or circumstances can help explain the rest? Factors that don't appear to affect the age of menopause include exercise, obesity, alcohol, coffee, or vitamin D status. Interestingly, women who've been married tend to arrive at menopause later. Some suggest it may be the influence of male pheromones, given the fact that exposure to male armpit odor makes women's cycles more regular. But it turns out that male cohabitation alone doesn't appear to matter. It may be the sex. Married older individuals tend to have more sex, and indeed pre- and perimenopausal women average age 46, who reported sex weekly were 28% less likely to experience menopause over the subsequent decade than those reporting sex less than once a month. You can very well imagine how this could be a result of reverse causation, though. Instead of more sex leading to later menopause, a later menopause may have instead led to more sexual engagement. The relationship between tobacco use and early menopause is thought to be mediated by the toxic effects on the ovaries of the polycyclic aromatic hydrocarbons in the smoke. Among non-smokers, this PAH exposure is almost entirely from food, mostly grilled barbecued and smoked meats. Could this explain why? In the Harvard Nurses Health Study II, higher plant protein intake was associated with significantly lower risk of early menopause, feed female monkeys that died high in animal protein, and not only did they get more atherosclerosis, but also an acceleration of ovarian aging. Now, in the original Harvard Nurses Health Study, animal protein consumption was associated with infertility, such that replacing even 5% of animal protein intake with plant protein could potentially cut the risk of infertility in half. But in the Nurses Health Study II, while plant protein appeared to delay menopause, animal protein intake was not associated with menopause age either way. And in the UK women's cohorts today, those eating more animal protein were 6% more likely to experience a later menopause. The data is similarly conflicting in vegetarians. Some studies found no difference or a later age of menopause in vegetarians, but others found an earlier age compared to non-vegetarians. For example, the largest study found that vegetarians reached menopause at an average age of 50.1 years, compared to non-vegetarians, it's 50.7 years. As I noted, premature menopause before age 40 may be detrimental for longevity, but being a little earlier within the normal range may actually be beneficial for cancer risk. At the same age, breast cancer risk is about 40% higher in premenopausal compared to postmenopausal women, presumably due to higher exposure to the necessary evil hormone estrogen. Breast cancer risk is 3% higher for every year later a woman starts menopause and 5% higher for every year earlier a girl starts menstruating. On average, women whose periods hold off until age 15 appear to live the longest. Vegetarian women tend to have lower estrogen levels, perhaps due to higher fiber intake, and the interventional studies show that switching to a more plant-based diet can reduce circulating estrogen levels by more than 40%. This could explain why vegetarian girls may hit puberty later and why those eating strictly vegetarian not only have lower cancer risk overall, but particularly lower risk for female-specific cancers. Age of menopause may not be a factor, though, based on an interventional trial randomizing women on the verge of menopause, average age 49, to two years of a lower fat diet to reduce breast cancer risk. The intervention group ended up eating more fiber and therefore more plant-based, but though they did experience improvements in mammogram findings, the dietary shift failed to influence the timing of menopause.