Anti-Müllerian Hormone (AMH) is a hormone produced by cells within ovarian follicles, the small sacs in the ovaries that hold immature eggs. AMH serves as an indicator of ovarian reserve, reflecting the remaining egg supply. Measuring AMH levels through a blood test provides insights into reproductive potential and aids in reproductive health assessments.
Understanding AMH Levels
A normal AMH range is between 1.0 and 3.0 ng/mL, suggesting a healthy egg supply for a woman’s age. Levels above 3.0 ng/mL, considered high, are often observed in women with Polycystic Ovary Syndrome (PCOS), indicating a greater number of follicles. High AMH levels alone do not diagnose PCOS, requiring additional clinical findings and tests.
Conversely, AMH levels below 1.0 ng/mL are considered low, suggesting diminished ovarian reserve. Severely low levels are below 0.4 ng/mL. While low AMH indicates a reduced quantity of eggs, it does not necessarily mean a woman is unable to conceive naturally, as it reflects egg quantity rather than egg quality.
AMH Levels and Age
AMH levels decline as a woman ages, reflecting the decrease in her ovarian reserve. This decline begins in the late 20s to early 30s and accelerates in the mid to late 30s. By the time a woman reaches her 40s, AMH levels are much lower, indicating a reduced number of available eggs.
For instance, average AMH levels are around 4.23 ng/mL for women aged 20-25, decreasing to 2.43 ng/mL for those aged 31-35, and further to about 0.52 ng/mL for women aged 40-44. This age-related decrease explains why fertility assessments are recommended earlier for women planning to delay childbearing. Despite this trend, there can be a wide variation in AMH values for women of the same age.
AMH in Fertility Assessment
AMH levels are used in fertility assessments to help predict how a woman’s ovaries might respond to treatments like in vitro fertilization (IVF). Women with higher AMH values tend to respond better to ovarian stimulation, leading to the retrieval of more eggs during an IVF cycle. This increased number of retrieved eggs correlates with a higher success rate in IVF, as it provides more embryos to select from for transfer.
Conversely, lower AMH levels may indicate a lower expected response to ovarian stimulation and fewer eggs retrieved. However, a low AMH level alone does not predict a low IVF success rate, particularly for women under 35. AMH primarily indicates egg quantity and does not directly predict natural pregnancy success or egg quality.
Other Influences and AMH Limitations
Beyond age, several other factors can influence AMH levels. Medical conditions like Polycystic Ovary Syndrome (PCOS) are associated with elevated AMH levels due to an increased number of immature follicles. Endometriosis can also affect AMH levels, potentially leading to lower readings. Genetic factors and a family history of premature menopause also play a role.
Lifestyle elements like vitamin D deficiency, hormonal birth control use, and smoking can also impact AMH levels. For example, hormonal birth control can artificially suppress AMH levels by 30%, though these levels recover after discontinuing use. AMH testing has limitations; it does not assess egg quality, the health of the uterus, fallopian tube patency, or male factor infertility. Therefore, a comprehensive fertility evaluation involves multiple assessments beyond just AMH levels.