What Is Low AMH? Understanding Its Impact on Fertility

What Is Anti-Müllerian Hormone (AMH)?

Anti-Mullerian hormone is a protein hormone synthesised by the granulosa cells in the small, pre-antral and early antral follicles in the ovaries. These follicles are the "resting" eggs that have not yet been selected for ovulation. Because AMH is produced by these developing follicles, the amount of the hormone present in the blood generally correlates the total number of eggs left in the ovaries.

In reproductive biology, AMH helps regulate follicle development. It helps control the number of follicles recruited, so the ovaries progressively decline in ovarian reserve. As opposed to other fertility hormones that vary irregularly during the month, AMH levels do not change a lot during the menstrual cycle. It is a useful diagnostic tool because it can assess ovarian reserve, or the ovarian reserve, at one time due to its stability.

How Is AMH Measured in a Clinical Setting?

Clinicians assess AMH by using a basic blood test. In contrast to Follicle-Stimulating Hormone (FSH), which physicians must test on the second or third day of a menstrual cycle, an AMH test can be done on any day. This is convenient and, therefore, is one of the most ordered tests in a fertility workup.

The lab measures the concentration of AMH in serum, typically in nanograms per millilitre (ng/mL). This test is often performed in combination with a transvaginal ultrasound by doctors to conduct an Antral Follicle Count (AFC). Although the AMH test provides a biochemical measure of ovarian reserve, AFC provides a visual count. A combination of the two metrics provides a more accurate assessment of a patient's current reproductive potential.

What Is Considered a Low AMH Level?

Although laboratory normal ranges may vary slightly, the medical community generally provides standardised benchmarks for interpreting AMH results. The levels assist in classifying the ovarian reserve into certain levels:

• High (Potential PCOS): Over 3.0 ng/mL.
• Normal: 1.0 ng/mL to 3.0 ng/mL.
• Low: 0.5 ng/mL to 0.9 ng/mL.
• Very Low (Severely Diminished Reserve): Less than 0.5 ng/mL.

The result of a low reading means that the ovaries have a lower number of resting follicles than usual. However, clinicians interpret these values based on age. It may be reasonable to expect a level of 0.8 ng/mL in someone in their mid-40s, but it is worryingly low for someone in their late 20s.

What Causes Low AMH Levels to Develop?

There are several causes of a decrease in AMH. Some of them are normal aspects of ageing, whereas others are pathological or environmental.

• Natural Ageing: Time is the most prevalent cause. An individual is born with a certain number of eggs, which decreases each month after puberty until menopause.
• Genetics: Genetic predispositions increase the rate of follicular depletion (or have a smaller initial pool of eggs), e.g., Fragile X premutation.
• Autoimmune Disorders: Diseases in which the immune system targets ovarian tissue, are capable of depleting the egg count prematurely.
• Environmental Toxins: Over time, exposure to some chemicals, heavy metals and tobacco smoke may cause ovarian follicles to die faster.
• Medical Therapies: Chemotherapy and radiation therapy are considered to be gonadotoxic, i.e. they may severely harm or destroy the ovarian reserve.

Does Low AMH Indicate Poor Egg Quality?

This is one of the most misunderstood aspects of fertility testing. Quantity, not quality, is measured in AMH. Low AMH means there are fewer eggs, but it does not indicate anything about the health of the chromosomes or the viability of the eggs. In this case, a 28-year-old patient with low AMH (0.6 ng/mL) is unlikely to have low-quality eggs, as her age indicates that the majority of her remaining eggs will have normal chromosome composition. On the other hand, a 43-year-old with a normal AMH level (1.1 ng/mL) might have numerous eggs, but most are likely to be chromosomally abnormal due to age-related wear and tear.

Low AMH makes it more difficult to find a good egg during a fertility cycle, but it does not mean a viable egg may still be present.

Can a Person Get Pregnant Naturally with Low AMH?

Yes, with low AMH, natural conception is still possible. Since a natural pregnancy will only need the release of one fertilised egg each month, an individual with a low reserve can still release a high-quality egg and become a mother.

Low AMH does not predict the chance of pregnancy in a given month, but it predicts how much time an individual has before they may experience depletion of ovarian reserve. It also anticipates the poor response they would give to high doses of hormones administered during IVF. A low AMH may have a reduced period of fertility, but they are not always infertile in the short term.

How Does Age Affect AMH Results?

Age is the primary factor used to interpret AMH levels. The normal range of AMH declines with age.

• In the 20s: AMH is generally at its highest, which usually remains high above 2.0 ng/mL.
• Early 30s: A gradual decline begins, but levels tend to remain within the normal range.
• After age 35: The deterioration is more rapid.
• Age 40 or older: Many people experience levels below 1.0 ng/mL.

When AMH is very low, compared to the average of the age group, a diagnosis of Diminished Ovarian Reserve (DOR) is made. A 25-year-old with a reading of 1.0 ng/mL is a significant alarm; a 42-year-old with 1.0 ng/mL is a good indicator.

What Medical Conditions Lead to Low AMH?

Beyond the natural ageing process, specific clinical conditions can compromise the ovaries.

• Endometriosis: This disease, especially when it involves endometriomas (chocolate cysts), can result in the physical destruction of the ovarian cortex and loss of follicles.
• Ovarian Surgery: When cysts or part of the ovary are removed, healthy follicles are usually destroyed unintentionally, and the blood supply to the ovary may be compromised.
• Pelvic Inflammatory Disease (PID): Severe infections may cause scarring and inflammation that adversely affect the health of the ovaries.
• Polycystic Ovary Syndrome (PCOS) Paradox: Although Polycystic Ovary Syndrome (PCOS) typically results in elevated AMH, the therapies to control it, or the chronic inflammatory condition, sometimes cause a premature decrease in reserve.

Can Lifestyle Changes Improve AMH Levels?

Lifestyle changes cannot "grow" new eggs. However, they can potentially stabilise the environment in which the remaining follicles live.

• Smoking Cessation: Smoking is directly associated with increased egg loss. Quitting smoking can slow further decline.
• Vitamin D Supplementation: There is some evidence of a correlation between lower AMH levels and Vitamin D deficiency. Correcting a deficiency may lead to a more "accurate" or slightly higher test result.
• Anti-Inflammatory Nutrition: The systemic inflammatory response can be reduced by following a Mediterranean-style diet, which may improve overall reproductive health.
• Stress Management: Stress itself does not damage ovarian function, but elevated cortisol levels may interfere with the delicate hormonal communication between the brain and the ovaries.

What Fertility Treatments Work for Low AMH?

When AMH is low, fertility clinics often adjust their protocols to maximise the chances of retrieving the few eggs that remain.

• Intrauterine Insemination (IUI): IUI may be an effective initial treatment in young patients with low AMH when the fallopian tubes are clear.
• Mini-IVF (Low-Stimulation IVF): Ovaries with low AMH typically do not yield a high number of eggs, no matter the amount of medication, so the amount of hormones used will be lower. This aims to achieve two to five good eggs rather than a large number of poor-quality eggs.
• DuoStim: This is a process performed on two egg retrievals during one menstrual cycle to retrieve multiple eggs in a brief period.
• Donor Eggs: If AMH levels are undetectable and the patient is already of advanced age, donor eggs offer the best chance of success by avoiding the ovarian reserve problem altogether.

Is There a Way to Increase AMH Levels?

There is no proven medical way to increase the total number of eggs in the ovaries once they are gone. Nonetheless, some supplements are commonly used to improve the performance of the remaining eggs and the precision of the AMH test.

Coenzyme Q10 (CoQ10) and DHEA are commonly used in patients with low AMH. DHEA, a precursor hormone, can make follicles more responsive to stimulation, and in some cases, patients experience a slight increase in AMH levels after several months of supplementation. It does not imply that new eggs were formed, but it indicates that those follicles that were previously dormant or silent are now forming enough hormones to be observed.

Conclusion

A low AMH result can be concerning, but it does not eliminate the possibility of pregnancy. It recognises a depletion of the number of the egg supply- the ovarian reserve- but it is not a conclusive determination of the quality of those eggs or the capacity to carry a healthy pregnancy.

In the younger people, low AMH is a wake-up call to act promptly, perhaps by considering egg freezing or hastened fertility procedures. For individuals later in their reproductive years, it would help determine realistically whether reproductive procedures, such as IVF, would be successful. By combining AMH testing with other diagnostics, such as AFC and FSH, medical experts can develop highly individualised plans. Finally, low AMH is also an empowering tool; it provides data that enables informed, timely decisions about family building and hormonal health, helping patients make the most effective choices moving forward.