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

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 7th 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: 1,061 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 7th day after FET were higher in the single OP group compared to the biochemical pregnancy (BP) group (p ＜0.001). Besides, the serum β-hCG cutoff level at 4.34 mIU/mL on the 7th day showed high predictive value (area under the curve [AUC] = 0.852). Serum β-hCG levels on the 7th day after FET were higher in the twin OP group compare...