What is AMH and why does IVF depend on it?

03 Sep What is AMH and why does IVF depend on it?

AMH, or anti-Müllerian hormone, is more important than it sounds. It’s a revealing protein=hormone geared to your reproductive system. An AMH test can help IVF patients evaluate their chances of success.

AMH is secreted by cells in a woman’s growing follicles. (Men produce a little AMH too.) Testing plasma levels of AMH before IVF is a useful indicator of ovarian reserve and potential response to IVF drugs. If AMH levels are within the normal range, your ovaries may react better to stimulating medication. Overly low or high levels aren’t so good.

But why bother with AMH when you can just check your FSH level? Here’s why. AMH testing is now globally accepted as a key blood-hormone test before IVF. If your clinic doesn’t agree, you’re with the wrong clinic. A 2017 study into AMH validated its importance.

An AMH test looks at the growth of small follicles. Growing follicles say a lot about reserve follicles waiting in the wings. FSH provides the power for growth. But AMH is a snapshot of ovarian supply. The test is an accurate marker of female fertility. Think of FSH as a reliable old Ford and AMH as a cutting-edge Aston Martin.

AMH levels drop off as you get older. Visible and microscopic follicles decrease. By the menopause, AMH levels and follicle count are negligible. Since it’s often women in their late thirties and early forties who have IVF with their own eggs, an AMH assessment is a must.

It was originally thought that an AMH test couldn’t tell you about the quality of your follicles. This has been refuted in recent research (see below). What’s more understood is that AMH levels highlight follicle quantity. Generally, low AMH means there’s not enough petrol (i.e. eggs) in the tank. And you can’t buy any more.

Worldwide AMH measurement methods vary, as they do for LH, prolactin and TSH. But unlike those hormones, AMH levels don’t tail off or increase in your cycle: you can have an AMH test at any point on your cycle. Your report, based on your age, will tell you if your AMH level is ‘normal’ for your age. That’s not the same thing as saying you have a ‘normal’ chance of success as an IVF patient.

Speaking every generally, an AMH score between 8 and 24 pmol/l may allow for a better response to IVF medication. A reading above 30 is on the high side, and may suggest PCOS. Above 70, you’re in the danger zone of severe PCOS and a high risk of hyperstimulation. A score below 5 will generally mean a low chance of successful treatment.

So your AMH test lets you and your doctor make an informed choice on whether or not to go ahead. A reasonably high, rather than a reasonably low, AMH score is generally best. More follicles usually mean more collected eggs after IVF stimulation. If there are more eggs to fertilise, there may be a better selection of embryos to transfer.

This is backed up by research on anti-Müllerian hormone and assisted reproduction from the Endocrine Society. It found a significantly better birth rates among IVF patients with higher AMH levels. People with a higher AMH concentration were more than twice as likely to give birth. Interestingly, the study concluded that high AMH levels may be linked to quality, and not just quantity, of eggs.

Many other AMH studies exist. A 2019 study into AMH, IVF and age caught our eye. It found that younger women with low AMH levels had more successful pregnancies that older women with the same AMH level. This may show that older women have more fertility challenges than younger women, regardless of their AMH level. That’s why AMH is not the sole marker for success.

This is reflected in the outcomes of some of our own IVF patients. We have helped a 42-year-old, with an AMH of below 2, to a successful live birth. But some patients younger that this, with good AMH scores for their age, don’t succeed. Fertility is complicated.

AMH continues to intrigue clinicians. IVF patients should have an AMH test before each fresh cycle. But be warned: it can cost more than the other blood-hormone tests put together. Just don’t pay more than £150 for one. Or see if AMH testing is included in your clinic’s treatment price.