Endometriosis Shifted Natural Menopause 5 Months, Surgery 7-Fold

Somewhere tonight a woman in her thirties is holding her phone at arm's length in a dark kitchen, reading a headline that says endometriosis is linked to early menopause. She has already had the laparoscopy and the years of being told the pain was ordinary. Now a second countdown appears to have been stacked on the first, and the coverage that delivered it does not say how much earlier. It says earlier, which the mind at eleven at night quietly converts into much.

The study underneath those headlines is large enough to answer the question with real precision, and its answer arrives in two pieces that the coverage tends to weld together. Endometriosis moved the average age of natural menopause by about five months. It multiplied the risk of reaching menopause through surgery roughly sevenfold. Those are very different findings wearing the same headline.

Hsin-Fang Chung, Kunihiko Hayashi, Annette Dobson, Sven Sandin, Yuki Ideno, Rebecca Hardy, Elisabete Weiderpass and Gita Mishra pooled individual-level data from five cohort studies running in the UK, Australia, Sweden and Japan between 1996 and 2022. That gave them 279,948 women, of whom 10,367 — 3.7% — had endometriosis, identified through a mix of self-report and administrative records. By the end of follow-up, 58.2% of the women had reached natural menopause and 7.9% had reached it surgically. The analysis was published in Human Reproduction in June 2025.

The definitions do a lot of work here. Surgical menopause meant premenopausal bilateral oophorectomy: both ovaries removed before menopause had arrived on its own. Natural menopause was dated from the final menstrual period. Women whose menopause type and age could not be determined — those who had a premenopausal hysterectomy with the ovaries left in place, and those using menopausal hormone therapy — were excluded from the analysis altogether. That exclusion removes a group whose experience of endometriosis is often among the most surgical, and it is worth carrying into every number below.

The statistical choice that matters most is the competing-risk model. A woman whose ovaries are removed at 38 will never have a natural menopause, so an analysis that simply waits for her final period would mishandle her. Fine-Gray subdistribution hazard models treat the two routes as rivals for the same woman. Alongside that, linear regression estimated mean differences in age at menopause, and multinomial logistic regression compared age bands — under 40, 40 to 44, 45 to 49, 52 to 54 and 55 or over — against 50 to 51 as the reference.

Women with endometriosis had a 7.54-fold higher risk of surgical menopause (95% CI 6.84 to 8.32) and were correspondingly less likely to reach natural menopause at all (HR 0.40, 95% CI 0.33 to 0.49). When menopause did come surgically, it came 1.6 years — about nineteen months — earlier than in women without endometriosis (β −1.59, 95% CI −1.77 to −1.42).

Among the women who reached natural menopause, endometriosis moved the average age by 0.4 years: roughly five months (β −0.37, 95% CI −0.46 to −0.28). The confidence interval is narrow, which is a statement about precision rather than about size. With a sample this large, a five-month shift can be measured confidently and still be small against the ordinary spread of menopause ages, which runs across most of a decade from woman to woman.

The tails are where the clinical weight sits. Women with endometriosis were about twice as likely to have surgical menopause before 40 (OR 2.11, 95% CI 2.02 to 2.20) and 1.36 times as likely to develop spontaneous premature ovarian insufficiency, meaning natural menopause before 40 (95% CI 1.17 to 1.59). Odds of early menopause between 40 and 44 were elevated on both routes. A rare outcome made moderately less rare is easy to lose behind an average, and here it is the part that carries the later-life consequences.

The same headlines usually fold infertility in alongside endometriosis, and a separate prospective cohort makes the same split even more cleanly. Nancy Scime, Hilary Brown, Alison Shea and Erin Brennand followed 13,243 midlife women in Alberta's Tomorrow Project roughly every four years from 2000 to 2022, 18.2% of whom reported a history of infertility, defined as ever trying to conceive for more than a year without success.

Past infertility was associated with earlier surgical menopause, but only young: an adjusted hazard ratio of 3.13 at age 35 (95% CI 1.95 to 5.02), 1.83 at age 40 (95% CI 1.40 to 2.40), and 1.13 at age 45 (95% CI 0.87 to 1.46), by which point the interval crosses 1 and the signal is no longer distinguishable from chance. Infertility also raised the odds of surgical rather than natural menopause (adjusted OR 1.40, 95% CI 1.18 to 1.66). It was not associated with the timing of natural menopause at all.

Read together, the two papers point the same direction. What both conditions predict most strongly is an operating room, not an accelerated ovarian clock. The Alberta authors draw the inference explicitly: the absence of any natural-menopause signal argues against diminishing ovarian reserve being the primary mechanism linking infertility to what follows it.

It matters because the surgical route is where the young ages are. Premature and early menopause are associated with adverse health outcomes in later life, and the pooled-cohort authors close on exactly that point, recommending long-term monitoring for women with endometriosis and management tailored to avoid medically induced or premature menopause where it can be avoided. What clinicians weigh in that decision is whether ovaries can be conserved when a uterus cannot, whether an operation for pain relief needs to take the ovaries with it, and what a woman's own priorities are on either side of that trade.

And it matters because five months is the number that answers the fear the headline created. For most women with endometriosis who reach menopause naturally, the evidence does not describe a clock running a decade fast. It describes a small average shift, a modestly elevated risk of a rare early failure, and a much larger likelihood of a surgical decision — which, unlike a clock, is something a person and a surgeon arrive at together.

The honest reading of this pair of papers is that the phrase early menopause is doing two jobs at once, and only one of them is large. On the natural route, endometriosis moves the average by about five months — precisely estimated, genuinely real, and small enough that it is not the thing worth losing a night to. On the surgical route the effect is enormous, and it runs through a decision rather than through biology: bilateral oophorectomy is something a person and a surgeon choose, under pain and under pressure, and the sevenfold figure is at least in part a measurement of how endometriosis gets treated rather than of what it does to an ovary. That distinction is not a technicality, because the two findings have different futures attached. A five-month shift changes nothing anyone can act on. A doubled risk of surgical menopause before 40 sits inside conversations that are still open — about ovarian conservation, about what an operation is meant to accomplish — and it is those conversations, not the average, that the numbers here should be read into.