Anti-Mullerian Hormone (AMH) Testing of Ovarian Reserve
What is AMH?
- AMH, or anti-mullerian hormone is a substance produced by granulosa cells in ovarian follicles.
- It is first made in primary follicles that advance from the primordial follicle stage. At these stages follicles are microscopic and cannot be seen by ultrasound.
- AMH production is highest in preantral and small antral stages (less than 4mm diameter) of development.
- Production decreases and then stops as follicles grow. There is almost no AMH made in follicles over 8mm.
- Therefore, the levels are fairly constant and AMH testing can be done on any day of the woman’s cycle.
How can AMH hormone levels be a fertility test?
Since AMH is produced only in small ovarian follicles, blood levels of this substance have been used to attempt to measure the size of the pool of growing follicles in women.
- Research shows that the size of the pool of growing follicles is heavily influenced by the size of the pool of remaining primordial follicles (microscopic follicles in “deep sleep”).
- Therefore, AMH blood levels are thought to reflect the size of the remaining egg supply – or “ovarian reserve.”
With increasing female age, the size of their pool of remaining microscopic follicles decreases. Likewise, their blood AMH levels and the number of ovarian antral follicles visible on ultrasound also decrease. To learn more about age and fertility, read Dr. Marcy Maguire’s blog: What Is a Woman’s Age for Peak Fertility and When Does Fertility Begin to Diminish?
Women with many small follicles, such as those with polycystic ovaries (PCOS) have high AMH hormone values and women that have few remaining follicles and those that are close to menopause have low anti-mullerian hormone levels.
AMH levels and pregnancy chances with in vitro fertilization
Women with higher AMH values will tend to have better response to ovarian stimulation for IVF (in vitro fertilization), with more eggs retrieved. It has been documented that women with lower AMH have lower antral follicular counts and produce a lower number of oocytes (eggs).
AMH levels probably do not reflect egg quality. Having more eggs at the IVF egg retrieval provides an opportunity for a greater number of eggs to fertilize and develop into embryos. More eggs does not always mean more embryos. Egg quality plays a role in the fertilization and development of embryos. The ultimate goal is to have at least one healthy embryo to transfer back into the uterus.
What is a normal AMH level?
Interpretation of anti-mullerian hormone levels
There are some inconsistencies to consider when interpreting AMH hormone levels. Since the AMH test has not been in routine use for many years, the levels considered to be “normal” are not yet clarified and agreed on by the experts. Also, not all current commercial assays give equivalent results.
The table below has AMH interpretation guidelines from fertility literature. It is important not to be caught up by the cutoff values shown below.
For example, the difference between 0.6 and a 0.7 ng/ml test result puts a woman in a “different box” in this table- but there is very little real difference in fertility potential. In reality, it is a continuum – and not something that categorizes well.
AMH Blood Level
|High (often an indicator of PCOS)||Over 3.0 ng/ml|
|Normal||Over 1.0 ng/ml|
|Low Normal Range||0.7 – 0.9 ng/ml|
|Low||0.3 – 0.6 ng/ml|
|Very Low||Less than 0.3 ng/ml|
The below graph shows the average AMH level for women not experiencing trouble conceiving, according to age.
More will be learned regarding anti-mullerian hormone levels and outcomes as we continue to use the AMH fertility test and study the relationship between AMH hormone values, fertility and ovarian responsiveness.
Ovarian reserve testing methods
Anti-mullerian hormone is one potential test of ovarian reserve. There are other tests that are currently used for evaluation of the remaining egg supply. Fertility specialists often use a combination of fertility tests to best assess a woman’s ovarian reserve, including a transvaginal ultrasound to count the number of antral follicles and other hormone levels.
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