The Impact of Anti-Müllerian Hormone on Pregnancy Loss in Fresh and Frozen-thawed Embryo Transfer Cycles: A Retrospective Cohort Study

Background Anti-Müllerian hormone (AMH) is a key biomarker of ovarian reserve in assisted reproductive technology (ART). However, its association with miscarriage risk following embryo transfer remains controversial. This study aims to investigate the correlation between pre-pregnancy serum AMH levels and the risk of miscarriage in patients undergoing in vitro fertilization (IVF). Methods This retrospective cohort study analyzed 10,260 fresh and frozen-thawed embryo transfer cycles resulting in singleton clinical pregnancies at Peking University Third Hospital Reproductive Center during January 2017 to December 2020. Patients were categorized into low AMH (< 1.00 ng/mL) and normal AMH (≥ 1.00 ng/mL) groups. Miscarriage rates were compared, and binary logistic regression was employed to assess the association between AMH levels and spontaneous miscarriage. Results In the fresh embryo transfer cohort (n = 4,982), the low AMH group had significantly higher overall miscarriage (26.0% vs. 19.2%, P <  0.001) and early miscarriage rates (21.9% vs. 15.6%, P <  0.001) than the normal AMH group. This association was prominent in women under 35, who demonstrated higher miscarriage (20.8% vs. 15.4%, P =  0.003) and early miscarriage rates (17.4% vs. 12.5%, P =  0.003). After adjusting for confounders, low AMH remained an independent risk factor for miscarriage in women under the age of 35 (OR = 1.33, 95% CI = 1.02–1.73, P =  0.036). No significant association was found in women ≥ 35. In the frozen-thawed transfer cohort (n = 5,278), the miscarriage rate (23.0% vs. 18.5%, P =  0.018) and early miscarriage rate (20.2% vs. 15.9%, P =  0.020) were significantly higher in the low AMH group. However, stratified analysis by age showed no significant association between AMH levels and any miscarriage outcome (all had P >  0.05). Conclusion Low serum AMH is an independent risk factor for miscarriage after fresh embryo transfer in women under 35, but not in women ≥ 35. For frozen-thawed embryo transfer, AMH levels are not associated with miscarriage risk, regardless of age. Clinical trial number: not applicable.