Egg reserve is often spoken about as if it were a fixed store of eggs that can be counted, measured, and predicted.
In reality, what we are trying to understand is ovarian activity — how many follicles are present, how many have left dormancy, and how many are actively growing at a given point in time.
Anti-Müllerian Hormone (AMH) is one of several markers used to describe ovarian activity, but confusion arises when it is treated as a measure of egg reserve or as a prediction of fertility.
To understand what AMH can and cannot tell us, it helps to return to basic follicle biology.
What egg reserve actually describes
Egg reserve refers to the number of follicles within the ovaries that are capable of entering development.
These follicles exist at different stages, from dormant primordial follicles to those that are actively growing. At any given time, only a small proportion of follicles are metabolically active.
Egg reserve describes quantity — how many follicles are available to be recruited into development — not how well an individual egg will mature within its follicle.
Primordial follicles and AMH
Primordial (dormant) follicles do not produce AMH.
AMH only appears once follicles leave dormancy and enter early growth. This distinction is essential for understanding what AMH represents — and what it does not.
A person can have a large number of primordial follicles that are not contributing to AMH at all.
What AMH reflects
AMH is produced by granulosa cells in small, developing follicles.
Its presence reflects how many follicles have left dormancy and are actively growing at that point in time.
AMH is therefore a snapshot of current follicle activity, not a measure of total eggs remaining and not a measure of egg quality.
Because it is a snapshot, AMH can change over time. It can fluctuate, rise, or fall as ovarian activity changes.
The other number linked to egg reserve: antral follicle count
Alongside AMH, antral follicle count (AFC) is commonly used when discussing egg reserve.
AFC is a visual count of small follicles seen on ultrasound. It reflects how many follicles are recruitable at that moment in time.
AFC and AMH often move in the same direction, but they are not the same measurement. AFC describes what can be seen. AMH reflects which follicles are active.
Why AMH is not an egg-quality number
Egg quality is shaped over months within the follicle.
It reflects the environment the egg develops in — cellular support, metabolic conditions, and structural continuity as the follicle grows and ovulates.
AMH does not assess these processes.
A low AMH result does not automatically imply poor egg quality. A higher AMH result does not guarantee it. AMH tells us how many follicles are active, not how well an individual egg has developed.
Quantity and function are not the same
Markers such as AMH and AFC answer a narrow question:
How many follicles are active or visible right now?
They do not tell us:
• how resilient those follicles are
• how effectively they support egg development
• how consistent ovarian activity may be over time
This is why two people with similar AMH levels can have very different reproductive experiences.
Premature Ovarian Insufficiency (POI) and AMH
Premature Ovarian Insufficiency (POI) describes a pattern of reduced ovarian activity before the age of 40.
It is associated with irregular or absent menstrual cycles, altered ovarian hormone patterns, and reduced follicular activity compared with what is typical for age.
POI is sometimes referred to as premature ovarian failure, but this language is misleading.
In POI, ovarian activity is not usually absent. It is often intermittent, with periods of low activity followed by periods of follicular growth and, at times, ovulation.
AMH is often low in POI because fewer follicles are actively growing at that point in time — not because the ovaries have permanently stopped functioning.
For this reason, AMH cannot confirm ovarian failure or predict permanent loss of ovarian activity. It reflects current activity, not final capacity.
Placing the numbers back in context
AMH and AFC can be useful when they are used for what they measure:
current follicle activity and availability at a point in time.
Problems arise when these numbers are treated as a verdict, a countdown, a trigger to implement interventions or a substitute for understanding follicle biology.
When placed back into context, they become what they were always meant to be — limited markers, not definitions of fertility.
Egg reserve is about quantity.
AMH is about current activity.
Egg quality is shaped elsewhere, over time.
