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 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 the AMH test can be done on any day of a 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.
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 chances with in vitro fertilization
Women with higher AMH values will tend to have better responses 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.
