Study of 300 Million Lab Tests Finds Abrupt Body Changes at Menopause

The work was published in Nature Medicine in 2026. It is an observational, cross-sectional analysis of existing laboratory data from two independent cohorts, totalling 300 million laboratory tests. It is not a clinical trial. Nobody was assigned to a treatment, so the results show patterns, not cause and effect.

The problem the authors set out to solve is a practical one. Most of what we know about menopause comes from small studies that follow women over time. These have tended to describe menopause as a gradual transition. Large medical databases hold far more data, but they rarely record the age at which a woman had her final menstrual period. Without that, the data cannot be lined up around the event.

The researchers built a computational method, which they say was inspired by astronomy, to get around this. Women reach their final period at different ages. Averaging across them blurs any sharp change into a smooth slope. The method reconstructs trajectories anchored to the final period, removing that blurring.

Using it, the authors report a step-like physiological "cliff" at the final menstrual period. It appeared in the endocrine (hormone), skeletal, hepatic (liver), renal (kidney) and lipid (blood fat) systems. In plain terms, that covers sex hormones, bone, liver and kidney measures and cholesterol-type fats.

Three other findings stand out. The same jumps were absent in men. They were concordant across the two populations studied. And they appeared markedly attenuated in women using menopausal hormone therapy. The authors also report that dysregulation began more than a decade before the final period, with sex hormone changes starting more than 10 years before menopause.

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For personal health, the point is timing. If changes begin a decade or more early, the years before the final period may matter for bone and metabolic health, not only the years after. That question is where the debate lies.

ABC News (Australia), which reported on the study, quoted its lead, Uri Alon of the Weizmann Institute in Israel. According to ABC, he said bone density is usually checked around age 60, and that the findings would support checking around 40 or 45 and then considering hormone therapy as prevention, on a physician's advice. That recommendation comes from the coverage. The study reports that hormone therapy users showed smaller changes. It does not test whether starting therapy earlier protects bones.

Australian experts quoted by ABC were unconvinced by the framing. Martha Hickey of The Women's Hospital in Victoria said "physiological cliff is not a scientific or medical term" and called the claim "unnecessarily alarming". Elina Safro of the Australasian Menopause Society said the cliff idea is "not plausible". ABC noted that the study used existing data and self-reported information about the last period, unlike the long-running SWAN study, which was designed to follow women through the transition. Hickey described retrospective studies as "poor-quality" and not designed to answer this question, and Safro agreed. ABC also reported Hickey's caution that healthier women may be more likely to use hormone therapy, which could affect comparisons.

Where the critics and the study agree is on the value of earlier attention. ABC reported that Safro saw the early start of change as a reason to stay alert to health in midlife. Ada Cheung of the University of Melbourne said menopause is a good time to review bone health, cholesterol, blood pressure and blood sugar. Those points reflect the experts' views, not new findings.

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Alon told ABC his team is planning a clinical trial of hormone therapy started before the final period, which would be a far stronger test of whether earlier treatment protects bone and other systems.

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