High initial β-hCG predicts IVF outcomes accurately and precludes the need for repeated measurements

Abstract

This study evaluated β-hCG changes during the early period of pregnancy in an attempt to predict successful pregnancy outcomes in ART. It determined the median values of the β-hCG and the 2-day β-hCG increments of clinical vs. biochemical pregnancies. The results of fresh day 3 embryo, frozen day 3 embryo and frozen day 5 embryo transfers were evaluated. The cutoff values of β-hCG and the 2-day increments predicting clinical pregnancy and delivery were determined. All women who underwent embryo transfer and had a singleton pregnancy from January 2017–December 2019 were included. As expected, clinical pregnancies had higher initial median β-hCG values compared to biochemical pregnancies (fresh day 3 (400 vs. 73 mIU/ml), frozen day 3 (600 vs. 268.5 mIU/ml) and frozen day 5 (937 vs. 317 mIU/ml). Nonetheless, the abortion rate was significantly lower in the group with β-hCG above the cutoff values in fresh (141 mIU/ml), and frozen (354.5 mIU/ml) cleavage stage transfers (17.2% vs. 44%, P<0.001 and 18.5% vs. 38%, P=0.003, respectively). Blastocyst transfers resulted in higher median initial β-hCG compared to cleavage embryo transfers (937 vs. 600 mIU/ml), and the initial β-hCG values from frozen cleavage embryos were higher compared to fresh cleavage embryos (600 vs. 400 mIU/ml). Earlier implantation in frozen cycles may be caused by freezing-thawing procedures. Moreover, in fresh cycles, negative effects of the hormonal milieu of fresh cycles may delay implantation. Results indicate that high initial β-hCG and high 2-day β-hCG increments demonstrated better outcomes, including more clinical pregnancies and fewer abortions.