Construction and validation of a model for jointly predicting early pregnancy loss at 6 weeks of gestation after IVF-ET based on serum FGF-21,AMH,and NRP-1

ZHANG Hongwei; WANG Nan; SHI Guoxi; ZHAI Junying; NIU Hongli; WANG Ying

doi:10.3969/j.issn.1006-5725.2025.22.003

Abstract：Objective To investigate the predictive value of pre-transfer serum fibroblast growth factor 21(FGF-21),anti-Müllerian hormone(AMH),and neuropilin-1(NRP-1)for early pregnancy loss at 6 weeks following in vitro fertilization-embryo transfer(IVF-ET),and to establish an early predictive model based on serum biochemical markers.Methods This prospective study consecutively enrolled 322 women who achieved clinical pregnancy after IVF-ET at our center between September 2022 and September 2024.Participants were randomly divided into a modeling cohort(n=225)and a validation cohort(n=97)at a 7:3 ratio.According to ultrasound findings at 6 weeks of gestation,patients in the modeling cohort were classified into an early pregnancy loss group(n=59)and an ongoing pregnancy group(n=166).Baseline clinical characteristics and pre-transfer serum levels of FGF-21,AMH,and NRP-1 were collected.Multivariate logistic regression was applied to identify inde-pendent risk factors for early pregnancy loss and to construct a predictive model.Model discrimination,calibra-tion,and stability were evaluated using receiver operating characteristic(ROC)curves,the Hosmer-Lemeshow goodness-of-fit test,and bootstrap resampling in both cohorts.Results Univariate analysis revealed that the FSH/LH ratio,antral follicle count,and number of retrieved oocytes were significantly associated with early pregnancy loss(P<0.001).Compared with the ongoing pregnancy group,women with early loss showed significantly elevated pre-transfer serum FGF-21 levels,whereas AMH and NRP-1 levels were markedly reduced(P<0.001).Multivariate logistic regression demonstrated that an FSH/LH ratio<1.8(OR=1.629,P=0.002)and higher FGF-21 levels(OR=1.338,P=0.002)were independent risk factors,while higher AMH(OR=0.741,P=0.010)and NRP-1 levels(OR=0.874,P=0.007)were protective.Stratified analysis indicated that among patients with FSH/LH≥1.8,FGF-21 levels were significantly higher and AMH and NRP-1 levels significantly lower(all P<0.001).Interaction analysis further suggested that the FSH/LH ratio significantly modified the associations between these biomarkers and pregnancy loss risk(P for interaction<0.05).Specifically,in the higher FSH/LH subgroup,the risk effect of FGF-21 was amplified,while the protective effects of AMH and NRP-1 were more pronounced.The combined predictive model achieved C-indices of 0.869(95%CI:0.826～0.926)in the modeling cohort and 0.835(95%CI:0.811～0.907)in the validation cohort.Its AUC for predicting early pregnancy loss was 0.934 in the modeling co-hort and 0.909 in the validation cohort,both significantly outperforming individual markers(AUCs:FGF-21=0.867,AMH=0.881,NRP-1=0.853;Z=2.024,1.831;P<0.001).Decision curve analysis showed that the model provided consistent net clinical benefit across threshold probabilities of 0.1～0.4,underscoring its clinical utility.Conclusions Elevated pre-transfer serum FGF-21 and reduced AMH and NRP-1 levels are strongly associ-ated with early pregnancy loss at 6 weeks after IVF-ET.The predictive model developed in this study demonstrates robust accuracy and stability,offering substantial clinical application value for early risk stratification.