Anti-Müllerian Hormone (AMH) testing is a standard tool in the initial assessment of fertility for women considering In Vitro Fertilization (IVF). AMH provides insight into a woman’s ovarian reserve, which is the remaining quantity of eggs. A low AMH level signals diminished ovarian reserve (DOR), impacting the strategy and expectations of an IVF cycle. This article explores the specific thresholds used by fertility specialists and details how low AMH impacts the protocol.
Understanding AMH and Ovarian Reserve
Anti-Müllerian Hormone is a protein secreted by the granulosa cells surrounding developing follicles within the ovary. Its concentration in the bloodstream directly reflects the size of the remaining pool of primordial follicles, representing the woman’s functional ovarian reserve. AMH provides a reliable, cycle-independent measure of the quantity of eggs a woman has remaining.
The AMH test is preferred over older markers, like Follicle-Stimulating Hormone (FSH), because its levels remain stable throughout the menstrual cycle. While AMH strongly predicts the number of eggs retrieved during an IVF cycle, it is primarily a marker of egg quantity. The quality of the eggs is predominantly determined by the woman’s age. This distinction is fundamental when planning IVF.
Defining Specific “Low” AMH Thresholds for Treatment
Fertility clinics use specific numerical benchmarks, measured in nanograms per milliliter (ng/mL), to categorize ovarian reserve. A healthy AMH range is typically between 1.0 and 3.0 ng/mL. Levels below 1.0 ng/mL are classified as low, indicating diminished ovarian reserve and predicting a lower response to ovarian stimulation medication.
The most significant threshold for poor response is often set at AMH levels below 0.5 ng/mL. Patients in this “very low” category are anticipated to produce a small number of eggs following stimulation, increasing the likelihood of cycle cancellation. Some studies define an “ultralow” level as 0.3 ng/mL or less, or even below 0.16 ng/mL.
There is no absolute numerical cutoff below which IVF is universally denied. Clinics have reported successful pregnancies in patients with AMH as low as 0.1 ng/mL or even undetectable levels. The numerical value serves as a guideline to manage expectations and tailor the treatment plan, not as an exclusion criterion.
IVF Protocols Tailored for Diminished Ovarian Reserve
When a patient presents with low AMH, the focus of the IVF treatment shifts from maximizing egg quantity to optimizing the development of the few eggs available. This personalized approach involves specific stimulation regimens designed for poor responders. The goal is to avoid high cancellation rates by gently encouraging the recruitment of high-quality oocytes.
One common strategy is the Antagonist “short” protocol, which uses a quick course of medication to prevent premature ovulation while simplifying the injection schedule. Alternatively, the Flare or Microdose Lupron protocol may be utilized. This protocol takes advantage of a brief, natural surge in the body’s own follicle-stimulating hormone (FSH) at the start of the cycle to enhance ovarian response.
For women with critically low AMH, a Mild Stimulation protocol uses lower doses of gonadotropin injections, sometimes combined with oral medications like Clomiphene Citrate or Letrozole. Natural Cycle IVF may also be recommended, involving monitoring the single naturally selected egg with minimal or no stimulation medication. These tailored protocols aim to recruit the best possible egg quality.
Success Rates and the Predictive Value of Low AMH
A low AMH level is a strong predictor of poor ovarian response, meaning fewer eggs will be retrieved. However, AMH is a less reliable predictor of the ultimate outcome: a successful live birth. The primary factor influencing the health of an embryo and the likelihood of a successful pregnancy remains the patient’s age.
For women under 35 with very low AMH, the chances of achieving a live birth per retrieved egg are significantly higher than for older women with the same AMH level. A patient under 35 with AMH less than 0.5 ng/mL may have a clinical pregnancy rate three times higher than a patient over 40 with the same AMH level. This highlights that a few high-quality eggs from a younger patient can be more successful.
While the live birth rate per single cycle is lower for women with low AMH, multiple cycles can significantly improve the cumulative chance of success. Studies show that women with very low AMH who undergo up to three IVF cycles can achieve cumulative live birth rates comparable to national averages. A low AMH level indicates that the path to pregnancy may require a personalized, multi-cycle approach.