Purpose: Few published articles have compared initial hCG values across all different types of ART cycles, including cycles with fresh or frozen embryo transfer. No articles have compared initial hCG values in cycles utilizing preimplantation genetic screening (PGS). The purpose of this study is to compare initial hCG values after fresh embryo transfer, frozen embryo transfer, and after PGS.
Methods: This was a single-center retrospective cohort study at an academically affiliated private IVF center. All fresh and frozen embryo transfers between January 2013 and December 31, 2015 were included. We compared mean initial serum hCG values 14 days after oocyte retrieval for fresh cycles and 9 days after frozen embryo transfer. We examined cycles of single embryo transfer (SET) and double embryo transfer (DET).
Results: Two hundred elven IVF (fresh embryo transfer), 128 FET (frozen embryo transfer cycles, no PGS), and 111 PGS cycles (ovarian stimulation with embryo cryopreservation, PGS, and frozen transfer in a subsequent estrogen-primed cycle) with initial positive hCG values were analyzed. In patients achieving a positive hCG after SET, initial hCG values were higher after PGS compared to FET (182.4 versus 124.0 mIU/mL, p = 0.02) and IVF (182.4 versus 87.1 mIU/mL, p < 0.001) as well as FET compared to IVF (124.0 versus 87.1 mIU/mL, p < 0.01). After DET, initial hCG values were higher after PGS (222.8 mIU/mL) compared to FET (182.1 mIU/mL, p = 0.02) and IVF (131.1 mIU/mL, p = 0.001).
Conclusions: Our study suggests that initial serum hCG values are higher after using PGS and higher after the transfer of a frozen embryo compared to a fresh embryo. This suggests that initial hCG values relate to the chromosomal status of embryos. Initial hCG values may help determine intervention and monitoring later in pregnancy.
Keywords: Frozen embryo transfer; Preimplantation genetic screening; Single embryo transfer; hCG.