Before You Panic About Your AMH, Let’s Chat.
Understanding AMH: What It Can (and Can't) Tell You About Your Fertility
Written by Dr. Fiona Callender, ND and pelvic therapist. Dr. Fiona supports our patients from fertility to postpartum, helping them navigate the unknowns and cut through the online noise.
As many people begin to explore their fertility - whether they're planning ahead or have been trying to conceive for a while - lab testing often becomes part of the conversation. In my office, I frequently recommend blood work because there are several markers we'd like to see in a healthy range before pregnancy (or at least early in pregnancy).
One test that many fertility clinics offer, and one that patients often ask about, is AMH.
What is AMH?
AMH, or Anti-Müllerian Hormone, is produced by the cells surrounding small, growing ovarian follicles. These follicles have been recruited but haven't yet matured (they're typically less than about 8 mm in diameter).
Because AMH reflects the number of these small growing follicles, it acts as a marker of your functional ovarian reserve - the pool of follicles that are available to continue developing toward ovulation.
One of the reasons AMH is so useful is that, unlike many reproductive hormones, it stays relatively stable throughout the menstrual cycle. That means it can be measured at any point, whereas hormones like FSH need to be checked during the early follicular phase to give meaningful information.
What does AMH actually do?
AMH isn't just a marker - we think it also plays an important role in regulating follicle development.
It acts as a "brake," slowing the maturation of follicles so they aren't all recruited at once, helping preserve ovarian reserve over time. AMH also reduces the responsiveness of growing follicles to FSH, helping regulate which follicle is eventually selected to continue maturing and ovulate.
So, higher AMH must be better... right?
Since AMH reflects the number of growing follicles, it's easy to assume that higher is always better.
Unfortunately, it's not quite that simple.
Because AMH slows follicle maturation, very high levels can also reflect a large number of follicles that aren't progressing normally. One of the most common reasons for elevated AMH is Polyendocrine Metabolic Ovarian Syndrome (PMOS), formerly known as Polycystic Ovarian Syndrome (PCOS).
In fact, the 2023 international evidence-based guidelines now recognize elevated AMH as an alternative to ultrasound when assessing one of the diagnostic criteria for PMOS.
That said, high AMH alone does not diagnose PMOS. A diagnosis requires two of the following three features:
Clinical and/or biochemical hyperandrogenism (physical symptoms or lab evidence of elevated testosterone or other androgens)
Ovulatory dysfunction (often presenting as long or irregular menstrual cycles)
Polycystic ovarian morphology on ultrasound or elevated AMH
How high AMH impacts PMOS
High AMH in PCOS reflects a larger number of small follicles, but this AMH does two things: 1) It keeps those smaller follicles from maturing and releasing an egg - hindering ovulation; and 2) It sends a signal to the brain to increase LH (luteinizing hormone). LH in excess can tell the ovary to produce more androgens, leading to symptoms like acne, facial hair growth, or scalp hair thinning, and may further impair normal follicle development and ovulation. This perpetuates the cycle of small follicles that don’t fully develop - meaning AMH is both a marker of PMOS and part of what keeps it going.
Not everyone with a high AMH has PMOS, but it's often a reason to have a broader conversation and consider additional testing.
What about low AMH?
This is often the result patients are most worried about.
Low AMH generally suggests there are fewer growing follicles available in the ovaries. It may be seen with diminished ovarian reserve, as menopause approaches, or in premature ovarian insufficiency (POI).
While AMH can be very helpful for predicting how someone might respond to ovarian stimulation during IVF - and may help guide which treatment protocol is used - it has limited value in predicting the chance of conceiving naturally.
A single low AMH result, particularly in someone with regular cycles and no other reason to suspect infertility, should not be used to determine whether they can become pregnant or how long it will take.
Things that can temporarily lower AMH
Although AMH is generally a stable hormone, several factors can temporarily reduce levels, including:
Hormonal contraception
Smoking
Certain medications (including GnRH therapies used to treat endometriosis)
Pelvic surgery
Other temporary health factors
In many cases, these changes aren't permanent. AMH may increase again after stopping hormonal contraception or or quitting smoking. Following pelvic surgery, AMH often recovers over several months if the ovaries have been preserved, although the degree of recovery depends on the extent of surgery.
What AMH can (and can't) tell us
AMH can help us understand:
Your functional ovarian reserve
How your ovaries may respond to IVF medications
Whether additional fertility testing may be helpful
AMH cannot tell us:
Whether you'll conceive naturally
The quality of your eggs
Exactly when menopause will occur
Whether you have PMOS or not
The bottom line
AMH is a useful piece of information, but it's never a diagnosis on its own. I always interpret AMH alongside your menstrual history, age, ultrasound findings, other hormone testing, symptoms, and fertility goals. Looking at the whole picture helps us make decisions that are individualized to you rather than based on a single lab value.
If you have questions about your fertility or would like some support, you can book in with me at Crafted Balance either in-person or virtually.