A study of more than 300 million lab tests found sharp changes in many measures around menopause. Researchers say the findings raise new questions about timing, but they don’t mean women need new tests or treatments.
Menopause can affect much more than periods and hot flashes. Sleep may become harder. Mood can shift. And changes in the body can show up in places women might not expect.
Now, a new study suggests that many of those changes may happen more abruptly around the final menstrual period than researchers previously understood.
Published Oct. 12 in Nature Medicine, the study analyzed more than 300 million laboratory tests from more than 1 million women in the United States and Israel. Researchers found statistically significant abrupt changes in 52 of the 90 lab tests examined in the U.S. analysis.
The findings point to changes across several body systems, including those involved in bone health, liver function, kidney function and blood fats.
But there’s an important distinction: spotting a pattern across a large population is not the same as predicting what will happen to one woman.
What happens around menopause?
To study the timing of these changes, researchers combined data from the U.S. National Health and Nutrition Examination Survey and Israel’s Clalit health system.
They developed a computer-based method to estimate how lab results changed in relation to the final menstrual period; the last period, identified retrospectively after 12 consecutive months without menstruation.
Three hormone patterns stood out. Anti-Müllerian hormone, or AMH, began declining more rapidly about 15 years before the final menstrual period. Follicle-stimulating hormone, or FSH, began rising more rapidly about 14 years before it. Estradiol, a form of estrogen, began declining more rapidly about 12 years before it.
Those are estimates of average patterns across groups, not a countdown for an individual woman.
The researchers also found that conditions such as osteoporosis and cardiovascular problems became more common after menopause. The study does not prove that menopause alone caused those conditions.
You can read the full study in Nature Medicine for the methods and complete findings.
Does this mean women need earlier testing?
Not based on this study alone.
The researchers reconstructed average patterns from existing data. They did not develop a test that can tell a woman exactly when she will reach menopause or whether she will develop a particular health problem.
The findings also do not establish that women should begin routine hormone testing years before menopause.
The American College of Obstetricians and Gynecologists explains that hormone testing generally is not recommended before starting hormone therapy for menopausal symptoms. Hormone levels can fluctuate during the transition, so doctors may consider symptoms, menstrual changes and medical history when discussing care.
In other words, a change researchers can see across a population does not automatically translate into a new test a patient needs.
What about hormone therapy?
The study found that many of the abrupt changes in lab measurements appeared smaller among women using menopausal hormone therapy.
That is a finding worth investigating. It is not proof that hormone therapy caused the difference or prevents the health problems examined.
Women who use hormone therapy may differ from those who do not in ways researchers cannot fully account for, including access to health care and other health or lifestyle factors. The researchers say prospective randomized trials are needed to test treatment effects.
Anyone considering treatment should discuss symptoms, medical history, benefits and risks with a qualified health professional. The study is not a reason on its own to start, stop or change medication.
Why this matters in California
California has also been moving to expand menopause care. The state’s 2026 health budget law, Senate Bill 164, includes provisions addressing coverage for certain medically necessary, FDA-approved treatments and requirements related to menopause information and medical-necessity reviews.
Some requirements have future effective dates. Specified utilization-review requirements, for example, begin Jan. 1, 2027. The details depend on the provision and the health plan or program involved.
The law and the study address different problems. The research looks at biological patterns; the law concerns access to care.
For California women, having coverage is one part of the picture. Knowing what care is available, understanding medical advice and being able to ask questions also matter. We have addressed some of those broader barriers in our reporting on health insurance options in California and why public-health messages can miss Latino communities.
The study did not specifically establish that California women or Latinas experience different biological changes. That question needs evidence of its own.
The study’s size is a strength, but its methods have limits. Researchers reconstructed average timelines from data collected across groups rather than following every participant through menopause with repeated measurements. Menopause timing in the U.S. dataset also relied partly on self-reported information.
The results were broadly consistent across the U.S. and Israeli datasets. Still, more research is needed to understand what the measured changes mean for individual health and whether specific interventions improve outcomes.
For now, the takeaway is straightforward: menopause may involve changes across more of the body than a shift in reproductive hormones alone. Researchers have found a way to examine when many of those changes occur more closely.
That is an important step in understanding menopause. It is not proof that every woman needs extra blood tests, a new treatment or a different medical plan.
