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.