Association between 7-day serum β-hCG levels after frozen–thawed embryo transfer and pregnancy outcomes: a single-centre retrospective study from China

Abstract

Objective Early monitoring of plasma human chorionic gonadotropin (β-hCG) level is vital in predicting pregnancy outcome. This study investigated the predictive value of serum β-hCG level on the seventh day after frozen–thawed embryo transfer (FET) for ongoing pregnancy (OP) and adverse pregnancy (AP).Design Retrospective study.Setting The Reproductive and Genetic Center of the Affiliated Hospital of Shandong University of Traditional Chinese Medicine, China.Participants 1061 pregnant women who underwent FET between January 2014 and January 2017.Primary and secondary outcome measures Pregnancy outcome.Results Serum β-hCG levels on the seventh day after FET were higher in the single OP group compared with the biochemical pregnancy group (p<0.001). Besides, the serum β-hCG cut-off level at 4.34 mIU/mL on the seventh day showed high predictive value (area under the curve (AUC)=0.852). Serum β-hCG levels on the seventh day after FET were higher in the twin OP group compared with the single OP group (p<0.001). Also, the serum β-hCG cut-off level at 17.95 mIU/mL on the seventh day showed high predictive value (AUC=0.903). Serum β-hCG levels on the seventh day after FET were lower in the ectopic pregnancy group compared with the single OP group (p<0.001) whereas, serum β-hCG cut-off level at 4.53 mIU/mL on the seventh day exhibited a high predictive value (AUC=0.860). Further, the serum β-hCG levels on the seventh day after FET were lower in the single early spontaneous abortion group compared with the single OP group (p<0.001) while the serum β-hCG cut-off level at 5.34 mIU/mL on the seventh day exhibited high predictive value (AUC=0.738).Conclusion Serum β-hCG on the seventh day after FET has good clinical significance for the prediction of OP and AP.