Development and validation of a nomogram for predicting the risk of threatened abortion after in vitro fertilization-embryo transfer

Abstract

Objective: This study aimed to develop and validate a nomogram for predicting the risk of threatened abortion after in vitro fertilization-embryo transfer (IVF-ET).

Methodology: Clinical records of 409 patients who underwent IVF-ET treatment due to tubal factors in Huzhou Maternity & Child Health Care Hospital from January 2017 to May 2025 were retrospectively selected. Patients were randomly assigned to the training (n=286) and validation (n=123) cohorts in a 7:3 ratio. The Least Absolute Shrinkage and Selection Operator (LASSO) method and multivariate logistic regression were applied to identify independent risk factors, which were then used to construct a nomogram for predicting the risk of threatened abortion. The nomogram was validated using the area under the receiver operating characteristic (ROC) curve (AUC) and decision curve analysis (DCA) to assess its clinical application value.

Results: Female age, endometrial thickness, number of embryos transferred, and progesterone (P) level 14 days after IVF-ET were identified as risk factors for threatened abortion (P<0.05). Based on the four independent factors, a nomogram was developed. The nomogram demonstrated sufficient predictive accuracy, with AUC values of 0.822 (95% confidence interval (CI): 0.737-0.907) and 0.822 (95% CI: 0.724-0.919) in the training and validation cohorts, respectively. The validation results showed that the consistency index (C-index) for the training and validation cohorts was 0.802 (95% CI: 0.715-0.889) and 0.807 (95% CI: 0.719-0.895), respectively. The calibration curves for the two cohorts are closer to the diagonal (the ideal curve).

Conclusions: The established nomogram for threatened abortion after IVF-ET has good predictive value and helps identify high-risk populations.