Abstract: Objective To investigate the association of human chorionic gonadotropin (HCG) level on day 3 of embryo culture
with embryo development. Methods Spent culture media were collected from individually cultured embryos on day 3 of in
vitro fertilization and embryo transfer (IVF-ET) cycles. HCG concentration in the culture media was measured using an ELISA
kit and its association with embryo development was assessed. Results In the 163 samples of embryo culture media from 60
patients, HCG was positive in 153 sample (93.8%) with a mean level of 0.85±0.43 mIU/ml. The concentration of hCG in the
culture media increased gradually as the number of blastomeres increased (F=2.273, P=0.03), and decreased as the
morphological grade of the embryo was lowered (F=3.900, P=0.02). Conclusion ELISA is capable of detecting HCG levels in
spent culture media of embryos on day 3 of in vitro culture. The concentration of HCG in spent culture media is positively
correlated with the status of early embryo development and implantation rate and thus serves as a useful marker for embryo
selection in IVF-ET procedure.