Does AMH Drop During Pregnancy?
Yes, AMH levels consistently and significantly decrease during pregnancy, with the decline beginning early in gestation and continuing throughout all trimesters.
Pattern of AMH Decline During Pregnancy
The evidence demonstrates a clear, progressive decline in AMH levels throughout pregnancy:
- First trimester: AMH levels begin dropping early, with approximately 86% of women showing maximum AMH levels at or before ovulation 1
- Progressive decline across trimesters: AMH drops significantly from first trimester (median 1.69 ng/ml) to second trimester (0.8 ng/ml) to third trimester (0.5 ng/ml) 2
- Magnitude of decline: AMH decreases by approximately 7.5% per gestational week during the first and second trimesters 3
- Third trimester: Significant continued decline occurs during weeks 28-36 of gestation 4
The decline is independent of maternal age, BMI, gestational diabetes status, or fetal gender 1, 4.
Recovery Pattern Postpartum
AMH levels do not immediately return to baseline after delivery:
- Immediate postpartum: AMH continues to drop immediately after delivery 2
- Early recovery: AMH begins increasing over the first 4 days postpartum 2
- 1 month postpartum: AMH levels have NOT returned to expected non-pregnant levels 5
- 5 months postpartum: Mean AMH concentrations become similar to expected non-pregnant levels, though the rank order of AMH concentrations remains dissimilar to the non-pregnant state 5
This indicates that AMH regulation during pregnancy and the postpartum period is distinctly different from the non-pregnant state 5.
Clinical Implications
Critical Pitfall: Timing of AMH Testing
Do not measure AMH during pregnancy or within 5 months postpartum for ovarian reserve assessment, as these values do not accurately reflect true ovarian reserve 5, 2. The suppression appears to represent ovarian suppression during pregnancy rather than permanent changes in reserve 2.
Pregnancy Viability Patterns
Interestingly, AMH behavior differs by pregnancy outcome:
- Viable pregnancies: AMH shows consistent directional changes (either consistently increasing or decreasing) from weeks 4-7 of gestation 1
- Nonviable pregnancies: AMH shows erratic, sporadic patterns with both increases and decreases in the same individual 1
Natural vs. Treatment Pregnancies
- Natural pregnancies: Overall trend shows decreasing AMH levels 1
- Treatment pregnancies: AMH either consistently increases or decreases from gestation week 4 through week 7 1
Mechanism
The physiological mechanism underlying this decline likely reflects ovarian suppression during pregnancy, with AMH secretion being distinctly regulated during gestation compared to the non-pregnant state 5, 2. The rapid recovery postpartum supports this being a reversible suppression rather than permanent follicle depletion.