Effect of anti-Müllerian hormone on early pregnancy loss in hormone replacement therapy-frozen-thawed embryo transfer cycles: An analysis including 6597 pregnant patients undergoing their first in vitro fertilization/intracytoplasmic sperm injection cycle

Objective: To investigate the relationship between anti-Mullerian hormone (AMH) level and early pregnancy loss in patients who underwent their first embryo transfer by hormone replacement therapy-frozen-thawed embryo transfer (HRT-FET) and analyze the threshold effect. Methods: A retrospective cohort analysis was performed on pregnant women undergoing HRT-FET at the Reproductive Medical Center of Henan Provincial People's Hospital from January 2016 to December 2021. The patients were divided into four groups based on AMH concentration according to the Poseidon criteria: group A (<= 1 mu g/L), group B (1-<= 2 mu g/L), group C (2-<= 6 mu g/L), and group D (>6 mu g/L). Univariate analysis, multivariate logistic regression analysis, smooth curve fitting, and threshold effect analysis were applied to investigate the influence of AMH on the outcome of early pregnancy loss in in vitro fertilization/intracytoplasmic sperm injection and HRT-FET cycles. Results: Of the 6597 pregnant women, early pregnancy loss occurred in 893, giving an early pregnancy loss rate of 13.54%. Univariate regression analysis demonstrated that age, female body mass index, AMH, antral follicle count, endometrial thickness at endometrial transformation day, total retrieved oocyte number, number of pregnancies, duration of infertility, type of infertility, and the number of embryos transferred were all factors influencing the early pregnancy loss rate (P < 0.050). Multivariate logistic regression analysis, after adjusting for confounders, further stratified the analysis of patients of different ages. With group A as the control group, the results showed that when age was younger than 35 years, the pregnancy loss rates in groups B, C, and D were lower than that in group A, with statistical significance (P < 0.050); when age was 35 years or older, there was no statistically significant difference in outcome indicators between the groups (P > 0.050). A threshold effect analysis revealed that the AMH threshold was 2.83 mu g/L. When the AMH concentration was less than 2.83 mu g/L, the early pregnancy loss rate decreased significantly with increasing AMH concentration; the early pregnancy loss rate decreased by 21% for each unit increase in AMH (odds ratio 0.79; 95% confidence interval 0.71-0.88; P < 0.001); when the AMH concentration was 2.83 mu g/L or more, there was no statistical difference in the change in early pregnancy loss rate (odds ratio 1.01; 95% confidence interval 0.99-1.03; P = 0.383). Conclusion: For pregnant women after their first embryo transfer, there is a curvilinear relationship between the influences of AMH levels on early pregnancy loss rates in patients younger than 35 years. When the AMH level was less than 2.83 mu g/L, the early pregnancy loss rate declined significantly with increasing AMH levels.