AMH - What You Need to Know
Updated: Jan 13
By : Shirin Dason, MD, FRCSC (OBGYN), GREI fellow
I was asked if AMH was a fad. It's not - but I understand why someone would ask me that. It's a very popular test in my field (gynecologic reproductive endocrinology and infertility), but it may not be in yours, and you may get conflicting advice about whether it should be measured. Here's my opinion :
AMH, or anti-mullerian hormone is a measure of ovarian reserve, or the number oeg eggs available that your body pulls from during a cycle (remember, one egg ovulates but the others still grow and then atrophy)
AMH declines with age and is undetectable at the time of menopause. Though studies are ongoing, at this time, it cannot be used to predict the exact timing of menopause. It is likely that lower AMH = earlier menopause
AMH is high in PCOS because all those "cysts" are really follicles
AMH is lower in endometriosis and those who have had surgery/chemo/radiation to their ovaries. It may also be lower in BRCA, but this is controversial
We do not know the rate of decline of AMH so any measure is only a snapshot in time. It may be different in 6 months or a year. This is especially dependant on your age as decline happens more steeply after the age of 35.
AMH measures are impacted by the use of hormonal medication (i.e. the birth control pill) and numbers can be artificially lower by 20-50%; if you need to know what your AMH is, it should be measured 3-6 months after stopping the medication
AMH values is considered to be fairly stable overall but some fluctuations are possible and there is likely value in repeating abnormally low numbers for your age or using another test, like antral follicle count, to corroborate
AMH cannot predict spontaneous fertility - this is really important. AMH does not affect that single egg that ovulates each cycle.
AMH is primary used for two purposes : (1) prediction of response to fertility medications and (2) your family planning timeline
(1) response to fertility medications is useful for IVF & egg freezing because it predicts egg production. If the goal is more than one egg (which it is during these treatments), a higher AMH is better. This caps out around 15-20, higher than that poses a risk. This helps your doctor plan the right amount of medication to achieve your goals without putting you at risk of Ovarian Hyperstimulation Syndrome (OHSS).
low AMH = low response
higher AMH = high response
(2) fertility timeline : AMH can help you plan whether you should consider egg freezing or embryo freezing or if you have time to delay childbearing. Information is power - or anxiety-provoking
a really low AMH may mean egg freezing will yield very many frozen eggs, and thus the financial and emotional investment may not be worth it for you - this is for you to decide; your doctor may encourage you to start trying to have kids sooner rather than later, especially if you want more than one child
a higher AMH may mean that you could wait a few years to see where your life takes you and then revisit the decision to egg freeze later
ultimately, it's your decision what you want to do. Information is power - or unnecessary...!
If your AMH is low and you are under the age of 32, you may want to consider egg freezing or having kids soon or be open to egg donation, adoption or child-free living in the future
If your AMH is high and you are under the age of 32, you can likely wait and revisit this decision as you may not come back to use the eggs
If you are older than 27 and your AMH is high - does this mean you can egg freeze or do IVF?
Higher AMH means more eggs - this is very helpful if you are older
Egg quality matters though and a large number of lower-quality eggs means you will need more eggs to achieve a pregnancy that is likely to lead to a live birth
This becomes more important the older you are - by the age of 43, upwards of 90% of eggs are abnormal in chromosomal makeup
You will have a better chance with IVF/egg freezing though if your AMH is higher at any age - but you will also need more eggs to achieve a healthy pregnancy than you would have if you were younger
So, should you have your AMH measured?
If you are in the midst of family planning and the answer would change what you do (egg freeze, embryo freeze OR start trying to have kids now) then yes! If not - no, it's probably not going to be useful for you to know.
Ultimately this is up to you - if you'd like to have more information, get your AMH measured. If you think that after knowing all of this, you're not ready to know and it may cause you more anxiety rather than reassurance - don't have it measured until you're ready to make decisions about the answer!