Ectopic pregnancy following in vitro fertilization-embryo transfer: A retrospective diagnostic study to develop a predictive nomogram

Objective: This study aimed to investigate the risk factors associated with ectopic pregnancy (EP) following in vitro fertilization-embryo transfer (IVF-ET) to establish a model to predict the risk of EP. Methods This retrospective cohort study was conducted in our hospital between January 2010 and December 2020. The enrolled dataset was randomly divided into two: a training cohort (65%, N = 603) and validation cohort (35%, N = 331). Clinical characteristics and laboratory indexes were associated with EP following IVF-ET based on univariate and multivariate analyses, and nomograms for predicting EP were established. Discrimination and calibration were assessed using the concordance (C)-index and a calibration curve. Results Multivariate logistic regression analysis showed that female factors, previous ectopic pregnancy, high estrogen levels, frozen-thawed embryo transfer, and low human chorionic gonadotropin levels at 14 days post embryo transfer were risk factors for EP. Multivariate logistic regression analysis was used to develop the nomogram. A C-index of 0.819 and 0.882 in the training and validation cohorts respectively, indicated the model had reliable discrimination, and the calibration plot overlapped the diagonal reference line of perfect calibration, indicating effective calibration. Conclusions We developed and validated a nomogram for predicting the probability of EP that provides clinicians with a quantitative tool.