How does a miscarriage impact anti‑Müllerian hormone (AMH) levels and when should AMH be measured afterward?

AMH Levels After Miscarriage

Direct Answer

AMH levels do not change as a direct result of miscarriage itself—AMH reflects the underlying ovarian reserve, which remains stable regardless of pregnancy loss. The key clinical insight is that low AMH before conception is associated with increased miscarriage risk, but the miscarriage event does not alter AMH levels 1, 2.

Understanding the Relationship Between AMH and Miscarriage

AMH as a Stable Marker

• AMH does not vary significantly by menstrual cycle day and is not affected by exogenous estrogen or progesterone, making it a stable marker that reflects the pool of growing follicles in the ovary 1.
• AMH is produced exclusively by granulosa cells of small, growing ovarian follicles and accurately reflects the antral follicle pool 1.
• The hormone level represents the quantitative ovarian reserve and potentially the qualitative aspects of remaining oocytes 3.

Low AMH Predicts Miscarriage Risk (Not Vice Versa)

• Women with severely diminished ovarian reserve (AMH ≤ 0.4 ng/mL) face over twice the miscarriage rate compared to women with AMH ≥ 1 ng/mL (hazard ratio 2.3; 95% CI 1.3-4.3) 2.
• Meta-analysis data shows women with low AMH have 35% increased odds of miscarriage in ART pregnancies (OR 1.35; 95% CI 1.10-1.66) 3.
• In women ≥35 years, low AMH confers 85% increased miscarriage risk (OR 1.85; 95% CI 1.35-2.52) 4.
• The mechanism likely involves reduced oocyte quality from meiotic errors, leading to embryo aneuploidy and subsequent pregnancy loss 3.

Clinical Timing for AMH Testing After Miscarriage

When to Measure AMH

• AMH can be measured at any time after miscarriage without waiting for cycle normalization, as it does not require cycle-specific timing and remains stable throughout the menstrual cycle 1, 5.
• For women with regular cycles who have resumed menstruation, AMH testing remains valid at any point 1.
• For women with irregular cycles or amenorrhea post-miscarriage, AMH is particularly useful since timing is not critical 1.

Age-Specific Considerations

• For women ≥25 years, AMH testing is the preferred initial assessment and provides reliable information about ovarian reserve 1, 5.
• For women <25 years, AMH interpretation is less reliable, and antral follicle count (AFC) by transvaginal ultrasound remains the gold standard 1, 5.

Clinical Algorithm for Post-Miscarriage Evaluation

Immediate Assessment (Can Be Done Anytime)

• Measure AMH level without waiting for specific cycle timing, as it provides stable information about ovarian reserve 1.
• Document patient age, as this critically affects interpretation and risk stratification 4, 2.
• Obtain history of previous miscarriages to identify recurrent miscarriage patterns 6.

Interpretation Framework

• AMH <0.4 ng/mL indicates severely diminished ovarian reserve with significantly elevated future miscarriage risk 4, 2.
• AMH 0.4-0.7 ng/mL suggests incipient ovarian insufficiency and warrants close monitoring 4.
• AMH <0.7 ng/mL is associated with 91% increased odds of miscarriage (OR 1.91; 95% CI 1.40-2.60) 4.
• Recurrent miscarriage patients demonstrate significantly lower AMH levels compared to normal populations, both in women ≤35 years and >35 years 6.

Complementary Testing

• Add AFC by transvaginal ultrasound for comprehensive evaluation, as it correlates well with AMH and provides direct visualization of follicle pool 1, 4.
• Measure FSH and estradiol on cycle days 2-3 if menstruating, particularly if AMH is low 4.
• Consider karyotyping and other standard recurrent miscarriage workup if indicated by clinical history 6.

Critical Clinical Implications

Counseling Points

• Low AMH detected after miscarriage reflects pre-existing diminished ovarian reserve, not damage from the pregnancy loss itself 2, 6.
• Women with low AMH face both reduced fertility potential and increased risk of future miscarriage 4, 2.
• Spontaneous pregnancy rates improve significantly with increasing AMH levels in recurrent miscarriage patients 6.

Management Decisions

• Immediate referral to reproductive endocrinology is warranted for women with AMH <0.7 ng/mL who desire future pregnancy, particularly if age ≥35 years 4.
• Women with severely diminished reserve (AMH ≤0.4 ng/mL) require realistic counseling about extremely limited fertility potential 4.
• Consider expedited fertility treatment rather than prolonged attempts at natural conception in women with low AMH 6.
• Discuss oocyte cryopreservation immediately if any follicles remain and fertility preservation is desired 4.

Important Caveats

Assay Limitations

• Different AMH assays may yield varying results, so values must be interpreted using the specific laboratory's reference ranges 1, 4.
• AMH assays lack international standardization, limiting direct comparison between different testing platforms 1, 5.

Population-Specific Findings

• In young women (<35 years) undergoing IVF, one study found no association between low AMH and miscarriage after fresh blastocyst transfer 7.
• However, another study in the same population found high AMH levels (not low) associated with increased miscarriage risk, possibly related to PCOS 8.
• The most robust evidence from naturally conceived pregnancies consistently shows low AMH increases miscarriage risk 2, 6.

What AMH Does NOT Reflect

• AMH reflects "functional ovarian reserve" rather than the total primordial follicle pool 1.
• AMH is not part of the formal diagnostic criteria for premature ovarian insufficiency, which requires amenorrhea plus elevated FSH 4, 5.