Anti-Mullerian Hormone 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 can not be seen by ultrasound. AMH production is highest in pre-antral 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 the AMH test can be done on any day of a woman’s cycle.
How AMH Levels Are Used to Assess Fertility
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 decreases.
Women with many small follicles, such as those with polycystic ovaries 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 Success Rates with IVF
Women with higher AMH values will tend to have better response to ovarian stimulation for IVF and have more eggs retrieved. In general, having more eggs with IVF gives a higher success rate.
AMH levels probably do not tell us much about egg quality, but having more eggs at the IVF egg retrieval gives us more to work with – so we are more likely to have at least one high quality embryo available for transfer back to the uterus.
Our fertility specialists have done research on using AMH levels to predict IVF outcome. Results showed:
- High AMH levels correlate with low cancellation rates, retrieval of more eggs, higher live birth rates and a high chance for freezing of leftover embryos.
- Low AMH levels (alone) do not predict low IVF success rates in women under 35
- Couples should not be excluded from attempting IVF due to low AMH values alone because live birth success rates were reasonable in these cases.
What is a Normal AMH level?
Interpretation of anti-mullerian hormone levels and chances for conception
There are some problems involved with interpretation of AMH hormone levels. Because the test has not been in routine use for many years, the levels considered to be “normal” are not yet clarified and agreed on by all experts.
The table below has AMH interpretation guidelines from the fertility literature and from our experience. Do not get carried away with the cutoff values shown here. For example, the difference between a 0.9 and a 1.1 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.
| Interpretation (women under age 35) |
AMH Blood Level |
| High (often PCOS) | Over 4.0 ng/ml |
| Normal | 1.5 – 4.0 ng/ml |
| Low Normal Range | 1.0 – 1.5 ng/ml |
| Low | 0.5 – 1.0 ng/ml |
| Very Low | 0.5 – 1.0 ng/ml |
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 and fertility, ovarian responsiveness, chances for IVF success, etc.
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 which include:
-
Antral Follicle Count (AFC): An ultrasound exam that counts visible follicles in the ovaries.
-
Day 3 FSH and Estradiol Levels: Blood tests done early in the menstrual cycle to evaluate hormone levels.
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Clomid Challenge Test: A more involved hormone test using Clomid to assess ovarian function.
None of the tests are perfect, and fertility specialists will often use a combination of tests to try to get a better estimate of the size of the remaining egg supply.
Note: Anti mullerian hormone has also been referred to (mostly in the past) as “mullerian inhibiting substance”, or MIS.
Treatment options for women with reduced ovarian reserve:
- Lupron “flare” protocol for ovarian stimulation in low responders
- In vitro fertilization with assisted hatching
- In vitro fertilization with donor eggs