Reproductive Rounds: Understanding antimüllerian hormone in ovarian-age testing

AMH

AMH is expressed in the embryo at 8 weeks by the Sertoli cells of the testis causing the female reproductive internal system (müllerian) to regress. Without AMH expression, the müllerian system remains and the male (woffian duct system) regresses. The discovery of AMH production by the granulosa cells of the ovary launched a new era in the evaluation and management of infertile women. First reported in Fertility & Sterility in 2002 as a much earlier potential marker of ovarian aging, low levels of AMH predict a lower number of eggs in IVF.

AMH levels are produced in the embryo at 36 weeks’ gestation and increase up to the age of 24.5 years, decreasing thereafter. AMH reflects primordial (early) follicles that are FSH independent. The median AMH level decreases per year according to age groups are: 0.25 ng/mL in ages 26-30; 0.2 ng/mL in ages 31-36 years; and 0.1 ng/mL above age 36. (PLOS ONE 2015 doi: 10.1371/journal.pone.0125216).

AMH has also been studied as a potential biomarker to diagnose PCOS. While many women with PCOS have elevated AMH levels (typically greater than 3 ng/mL), there is no consensus on an AMH value that would be a criterion.

Many women, particularly those electing to defer fertility, express interest in obtaining their AMH level to consider planned oocyte cryopreservation, AKA, social egg freezing. While it is possible the results of AMH screening may compel women to electively freeze their eggs, extensive counseling on the implications and pitfalls of AMH levels is essential. Further, AMH cannot be used to accurately predict menopause.
 

Predicting outcomes

No biomarker is necessarily predictive of pregnancy but more a gauge of gonadotropin dosage to induce multifollicular development. AMH is a great predictor of oocyte yield with IVF (J Assist Reprod Genet. 2009;26[7]:383-9). However, in women older than 35 undergoing IVF, low AMH levels have been shown to reduce pregnancy rates (J Hum Reprod Sci. 2017;10:24–30). During IVF cycle attempts, an ultra-low AMH (≤0.4) resulted in high cancellation rates, reduced the number of oocytes retrieved and embryos developed, and lowered pregnancy rates in women of advanced reproductive age.

Alternatively, a study of 750 women who were not infertile and were actively trying to conceive demonstrated no difference in natural pregnancy rates in women aged 30-44 irrespective of AMH levels (JAMA. 2017;318[14]:1367-76).

A special consideration is for cancer patients who are status postgonadotoxic chemotherapy. Their oocyte attrition can be accelerated and AMH levels can become profoundly low. In those patients, current data suggest there is a modest recovery of postchemotherapy AMH levels up to 1 year. Further, oocyte yield following stimulation may be higher than expected despite a poor AMH level.
 

Conclusion

Ovarian aging is currently best measured by combining chronologic age, AFC, and AMH. There is no current evidence that AMH levels should be used to exclude patients from undergoing IVF or to recommend egg donation. Random screening of AMH levels in a low-risk population for decreased ovarian reserve may result in unnecessary alarm.

Dr. Trolice is director of Fertility CARE - The IVF Center in Winter Park, Fla., and associate professor of obstetrics and gynecology at the University of Central Florida, Orlando.