Abstract: Objective To explore the correlation of human chorionic gonadotrophin (hCG) level in the follicular fluid on oocyte
retrieval day with the number of oocytes retrieved, maturation rate, embryonic development, and pregnancy outcome in
controlled ovarian stimulation cycles. Methods The data of 311 IVF/ICSI-ET cycles from 2012 to 2013 was analyzed and
stratified according to hCG level in follicular fluid on oocyte retrieval day (<7 nmol/L, 7-14 nmol/L, 14-21 nmol/L, and >21
nmol/L) determined with chemiluminesence method. The number of oocytes retrieved, oocyte maturation rate, fertilization
rate, cleavage rate, available embryo rate and pregnancy rate were compared between the groups. Results In the IVF/ICSI-ET
cycles, the cycles with hCG level of 14-21 nmol/L in the follicular fluid on the day of oocyte retrieval had significantly higher
oocyte maturation rate and fertilization rate than those in the other 3 groups (P<0.05), but the number of oocytes retrieved,
cleavage rate, available embryo rate and pregnancy rate, though slightly higher, showed no significant difference from the
other 3 groups (P>0.05). In the group with hCG level >21 nmol/L, the oocyte maturation rate and fertilization rate were
significantly lower than those in the other 3 groups (P<0.05), and the available embryo rate and pregnancy rate were slightly
lower without significant differences from the other 3 groups (P>0.05). Conclusion Follicular fluid hCG level on the day of
oocyte retrieval is associated with oocyte maturation, fertilization, embryonic development potential, and IVF outcome. An
excessively high follicular fluid hCG level on the day of oocyte retrieval may have negative effects on oocyte maturation and
embryo development.