Is the Human Chorionic Gonadotropin Level on Day 10 After Cleaved Embryo Transfer a Predictor of Perinatal Outcome?: A Retrospective Cohort Study.

This study aimed to determine whether human chorionic gonadotropin (hCG) levels at day 10 after day 2 cleaved embryo transfer can predict pregnancy and perinatal outcomes. Patients who underwent oocyte retrieval with minimal stimulation or natural cycles and fresh or vitrified-warmed transfer of a single, day 2 cleaved embryo at our clinic between November 2018 and December 2020 were included in this study. Patients were classified into four age groups for oocyte retrieval and into ten groups based on the hCG level on day 10 after embryo transfer; pregnancy complications and delivery and neonatal outcomes were examined. Of the 5,840 cycles, 3,722 (63.7%) and 2,118 (36.3%) were fresh-cleaved and vitrified-warmed embryo transfers, respectively. The mean hCG level was 24.8 mIU/mL and the clinical pregnancy and live birth rates per transfer were 29.6% and 23.4%, respectively. Maternal age at the time of oocyte retrieval, husband's age, treatment cycle, embryo type and grade, cell number, and hCG levels were correlated with pregnancy and delivery outcomes in the univariate analysis. Conversely, only maternal age and hCG levels were correlated with the outcomes in the multivariate analysis. hCG levels on day 10 post-transfer are a useful predictor of pregnancy and delivery outcomes after cleaved embryo transfer. Live birth rates vary with maternal age, even when hCG levels are the same, but they do not vary according to the treatment cycle or type of embryo transferred. Low hCG levels may be associated with vasa previa but did not affect delivery outcomes.