Low AMH at a young age: what it means and what it does not

Anti-Müllerian hormone is produced by the small follicles in the ovary and reflects how many of them there are. That is why it is used as a marker of ovarian reserve, alongside the antral follicle count on ultrasound. But AMH is a counter, not a judge of quality. It says nothing about the chromosomal health of the eggs, and that is what determines whether an embryo will develop normally. Egg quality follows age: a 28-year-old with low AMH usually has eggs that are good for her age, even though there are fewer of them.

There are technical limits that are rarely explained. Different laboratories use different assays and the values are not always directly comparable; the same woman can get noticeably different results in two laboratories. Hormonal contraception lowers AMH by roughly 20 to 30 per cent while it is being used, so a test taken on the pill can give a misleading impression. A single value, taken out of context, should therefore not be read as a diagnosis.

It does not mean you cannot conceive naturally. In young women with regular cycles, studies have not found a convincing link between a low AMH and a smaller chance of conceiving within a year; a well-known JAMA study showed this clearly in women without a history of infertility. If you ovulate regularly, you release an egg each month regardless of how many remain in reserve. AMH cannot predict the month in which you will conceive.

It also does not mean menopause is near, and it is not the same as premature ovarian insufficiency. That is a separate diagnosis, requiring infrequent or absent periods for at least four months together with a raised FSH confirmed twice and a low oestradiol, in a woman under 40. Low AMH with regular cycles and a normal FSH does not meet that definition. And finally, a low AMH is not your fault and is not linked to stress or lifestyle in the way social media suggests.

Here AMH is genuinely useful, because it predicts the number of eggs that will be collected after stimulation reasonably well. With a low reserve, fewer eggs are expected per cycle, therefore fewer embryos, and more than one cycle is often needed to accumulate enough of them. The POSEIDON system groups patients by age and reserve; groups 3 and 4 cover exactly these women with a low reserve, younger or over 35, and help the team choose a realistic approach.

In practice this affects the starting dose, the type of protocol and the expectations set for each cycle. For young women the good news is that embryo quality remains good; the constraint is number, not potential. The strategy is therefore often to accumulate embryos over consecutive cycles and transfer later. Very high medication doses do not solve the problem and do not raise the egg count beyond what the reserve allows; the team explains this from the start so that planning stays calm.

In some cases a cause is found: genetic factors, including the FMR1 premutation or abnormalities of the X chromosome, previous ovarian surgery, particularly removal of an endometrioma, chemotherapy or radiotherapy, autoimmune disease, and smoking, which is documented to reduce reserve. In many other cases no cause is found, and that is a legitimate answer rather than an unfinished search.

Whatever the cause, time matters, because ovarian reserve only declines. This does not mean panic or rushed decisions; it means not postponing evaluation by years. If you are planning a pregnancy now, it is worth speaking to a specialist without waiting the usual 12 months. If pregnancy is not in the plan for the coming years, this is the conversation in which fertility preservation, that is egg freezing, is discussed while the reserve is still there.