Combined analysis of estradiol and β-hCG to predict the early pregnancy outcome of FET: a retrospective study

Abstract Background How to accurately predicting the pregnancy outcomes of an IVF cycle are particularly important. Although a lot of work was conducted to predict pregnancy outcomes by assaying serum β-hCG levels after embryo transfer, rare study has focused on the prediction of serum E2 level after transfer. This study sought to analyze the predictive effect of serum E2 combined with β-hCG on early reproductive outcomes 12 days after embryo transfer. Methods A total of 1521 patients with β-hCG positive values on day 12 after frozen-warmed embryo transfer (FET) in natural endometrial preparation cycles (NCs) were collected in affiliated Women’s Hospital of Jiangnan University. Logistic regression analysis was constructed to establish the clinical pregnancy prediction model, and the cutoff value, optimal sensitivity and specificity were calculated by Receiver operating characteristic (ROC). Results Levels of serum E2 and β-hCG on the 12th day after FET with NCs were higher in clinical pregnancy group (CP Group) compared with biochemical pregnancy group (BP Group) (P < 0.001). Besides, the cutoff values for E2 and β-hCG on the 12th day after FET with NCs in cleavage group (CE Group) were 129.25 pg/mL and 156.60 mIU/mL respectively, with area under the ROC curve (AUC) of 0.801 and 0.941 respectively. For blastocyst group (B Group), the cutoff values for E2 and β-hCG were 174.45 pg/mL and 217.70 mIU/mL, with AUCs of 0.762 and 0.924 respectively. The logistic regression analysis revealed that serum E2 day 12 and β-hCGday 12 were significantly associated with clinical pregnancy. Conclusions Serum E2 is significantly different in CP Group compared with BP Group in FET with NCs. Earlier E2 combined with β-HCG can be used as a predictor of early pregnant state.