Predictive value of maternal serum human chorionic gonadotropin levels in pregnancies achieved by in vitro fertilization with single cleavage and single blastocyst embryo transfers

Objective To compare serum hCG levels after transfer of a single fresh cleavage embryo and of a single fresh blastocyst embryo and to determine the predictive value of serum hCG levels for pregnancy outcomes. Design A single center retrospective cohort study. Setting Tertiary university health center. Patient(s) All fresh single ETs between December 2008 and December 2013. Intervention(s) None. Main Outcome Measure(s) Mean serum hCG levels on day 16 after oocyte collection, after the transfer of a fresh single cleavage embryo and a fresh single blastocyst embryo were compared. Multivariable regression analysis was performed to determine the association of potential factors on hCG value and a clinical pregnancy. Result(s) One thousand twenty-six fresh single ETs were analyzed, 801 (638 pregnancies) from a single blastocyst transfer and 225 (167 pregnancies) from a single cleavage ET. The mean hCG levels resulting from a single fresh blastocyst transfer (299 ± 204 IU/L) were significantly higher than those from a cleavage transfer (245 ± 204 IU/L). This difference remained after adjusting for confounding variables. The threshold value predicting a clinical pregnancy for a cleavage embryo was 100 IU/L, and for a blastocyst transfer, 133 IU/L. Conclusion(s) Our study suggests that initial serum hCG values are higher after the transfer of a single fresh blastocyst embryo compared with after a single fresh cleavage ET, even after adjusting for confounding variables.