What AMH tells you — and what it does not

AMH, anti-Müllerian hormone, is produced by the small follicles in the ovary. Its level in the blood gives an estimate of how many follicles remain — what is usually called ovarian reserve. That is why it is among the first tests ordered in a fertility assessment.

Why one number is not enough

AMH speaks to quantity, not quality. An available egg may or may not be healthy, and AMH does not say which. A physician always reads it alongside age, the antral follicle count on ultrasound, and the rest of the clinical picture. Interpreting AMH on its own — without those three — is almost always misleading.

What a low AMH means

That the ovaries will probably produce fewer follicles in response to stimulation, so a different medication protocol may be chosen or fewer eggs expected at retrieval. What it does not mean is that pregnancy is out of reach. Success does not depend on the number of eggs collected alone; a small number of eggs can still produce healthy embryos and a pregnancy.

A high AMH is not simply good news

A high level is sometimes seen alongside polycystic ovary syndrome and can indicate an excessive response to stimulation medication. In that case the physician usually chooses a more cautious dose and monitors more closely. "Higher is better" is not true of this test.

Does AMH change?

Ovarian reserve declines over time, and that is a normal process. Some medical conditions and some treatments can affect it as well. That is why, when a treatment such as chemotherapy is ahead, the conversation about preserving fertility begins before it rather than after.