AMH is not a fertility test

Every week someone arrives in our rooms holding a printout with one number circled on it, convinced that number has decided their future. Usually they've been up half the night reading forums. Almost always, they've been told more by the internet than by anyone who has seen their whole picture.

The number is anti-Müllerian hormone, or AMH. It's a useful test. It is not the test people think it is.

What AMH actually measures

AMH is produced by the small developing follicles in your ovaries. Measuring it gives an indication of your ovarian reserve: roughly, how many eggs are in the pool at this point in time.

That's genuinely helpful information in a few specific situations:

• Predicting how your ovaries are likely to respond to stimulation in an IVF cycle, and helping choose a starting approach
• Adding context to a conversation about egg freezing and timing
• Helping investigate conditions such as polycystic ovary syndrome, where AMH is often high
• Giving some warning where reserve is falling unusually early

What it doesn't measure

AMH tells you something about quantity. It tells you very little about quality, and quality is what drives whether an egg fertilises, develops and results in a healthy pregnancy. Age remains the strongest single predictor of egg quality, and no blood test substitutes for it.

Just as importantly, AMH says nothing about whether your tubes are open, whether you ovulate reliably, whether the uterine cavity is normal, or whether there's a male factor involved. Male factor is present in a meaningful proportion of couples having difficulty conceiving.

A woman with a low AMH can conceive naturally. A woman with a reassuring AMH can struggle. Both happen, often.

Where the harm comes in

Direct-to-consumer testing has made it easy to order an AMH without anyone to interpret it. The result arrives by email, without context, without a reference range that accounts for your age, and without anyone to say this is one piece of a larger picture.

What we see afterwards is people making enormous decisions, rushing into treatment they may not need or abandoning hope they should still hold, on the strength of a number that was never designed to carry that weight.

A more useful approach

If you're wondering about your fertility, the more valuable first step is a proper conversation and a broader assessment: your cycle history, an ultrasound to look at your ovaries and uterus, thyroid and other relevant bloods, a semen analysis if there's a male partner, and a discussion about timing and what you actually want.

AMH can absolutely be part of that. It just shouldn't be the whole of it.

If you've had a result that frightened you, bring it in. Bring the printout. We'll go through what it means in your context, which is the only context in which it means anything at all.

This article is general information and isn't a substitute for advice about your own situation.