High AMH Before Chemotherapy: More Ovarian Reserve Does Not Mean Protection From Damage

A longitudinal study enrolled 467 women with breast or blood cancers receiving alkylating agents.

Some ovarian reserve recovered, but returning to pretreatment AMH levels was rare even after two years.

Does a high AMH level protect ovarian function during chemotherapy? A study from Lille University Hospital in France suggests that starting with more ovarian reserve does not prevent chemotherapy-related follicle loss.

Women with high pretreatment AMH generally retained more reserve afterward and had some advantages in menstrual recovery. They nevertheless experienced substantial ovarian damage.

The study, published in the October 2026 issue of Human Reproduction, highlights why a reassuring initial hormone result should not replace fertility-preservation counseling before cancer treatment.

What high AMH does—and does not—mean

Anti-Müllerian hormone (AMH) is produced by small ovarian follicles and is measured in blood as an indirect marker of the remaining follicle pool.

Higher AMH usually suggests greater ovarian reserve. It does not necessarily indicate better egg quality or a greater chance of natural conception.

Chemotherapy can damage follicles and lead to reduced ovarian function or premature ovarian insufficiency. The researchers asked whether women starting with particularly high AMH might be relatively protected.

They focused on levels suggesting polycystic ovarian morphology (PCOM), a pattern involving many small follicles. PCOM is not synonymous with polycystic ovary syndrome (PCOS).

Following women for two years after treatment

The researchers analyzed records from 467 women treated at Lille University Hospital between January 2012 and February 2022.

There were 261 women with breast cancer, with an average age of approximately 31, and 206 with hematological cancers, averaging approximately 24.

All received alkylating chemotherapy agents. These drugs damage cancer-cell DNA but can also affect normal ovarian tissue.

The women were grouped by pretreatment AMH, and hormone changes were followed from before treatment until 24 months after completion. Antral follicle counts and menstrual recovery were also assessed.

Of the 467 initially enrolled, 320 completed the full follow-up and were included in the final analysis.

Higher starting levels did not prevent follicle loss

AMH fell during chemotherapy in both cancer groups and showed some recovery afterward.

Women who started with high AMH continued to have relatively higher levels at 12 and 24 months. However, having more reserve remaining does not establish that fewer follicles were damaged.

Both groups experienced substantial follicle loss. A larger starting follicle pool and resistance to chemotherapy are different biological properties.

Returning to baseline was rare after two years

Among women with breast cancer, AMH was undetectable at 24 months in 8.3% of the initially high-AMH group and 30.4% of the comparison group.

This suggests a greater likelihood of retaining measurable reserve after starting with high AMH. It did not mean recovery to the original level.

No woman with breast cancer returned to her pretreatment AMH by two years. Only three women with hematological cancers did so, all from the initially high-AMH group.

AMH generally recovered during the first 12 months and then remained comparatively stable through 24 months. Partial recovery should therefore not be equated with a complete return to the pretreatment state.

Menstrual recovery is not the same as restored ovarian reserve

Among women with breast cancer, persistent amenorrhea at 12 months was less common in those with initially high AMH.

A similar direction was observed in hematological cancers, but the difference was not statistically clear.

Resumption of periods does not prove that ovarian reserve has fully recovered. Regular cycles can coexist with AMH remaining substantially below pretreatment levels.

The study did not directly compare pregnancy or live birth rates, so it cannot establish a higher post-treatment chance of pregnancy for women starting with high AMH.

Fertility-preservation counseling remains important

Cancer treatment and survival take priority, while future reproductive wishes also deserve consideration.

A high AMH result should not be used to dismiss ovarian injury risk when alkylating agents are planned.

Potential preservation approaches include egg, embryo or ovarian-tissue freezing. Suitability depends on cancer type and stage, time before treatment, age and ovarian function.

The researchers emphasized counseling before treatment and ovarian-function follow-up afterward regardless of initial AMH.

Limitations include the retrospective design, incomplete two-year follow-up and difficulty distinguishing high AMH suggestive of PCOM from clinically defined PCOS.

The central distinction remains clear: having more follicles does not guarantee protection from chemotherapy. Decisions about fertility preservation require discussion before treatment rather than relying on one reassuring hormone value.

Study source

C. Decanter and colleagues, Lille University Hospital: “Pre-treatment AMH levels suggesting PCOM do not prevent chemotherapy-induced ovarian damage despite higher long-term ovarian reserve: a longitudinal study in 467 women treated with alkylating agents.” Human Reproduction, 2026;41(10):1780–1789. DOI: 10.1093/humrep/deag131.

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