Prognostic utility of serum beta human chorionic gonadotropin level following single euploid embryo transfer for live birth

Objective: To evaluate live birth outcomes on the basis of initial serum human chorionic gonadotropin (hCG) level following single euploid embryo transfer.

Design: Retrospective cohort study.

Subjects: Single center study that included patients who underwent single euploid embryo transfer with initial positive hCG (>2.5 mIU/mL), measured nine days after transfer. Cycles were grouped by hCG range: Group 1 (hCG 2.5 to <11 mIU/mL), group 2 (11 to <25), group 3 (25 to <50), group 4 (50 to <75), group 5 (75 to <100), and group 6 (≥100).
Exposure: Initial serum hCG level.

Main Outcome Measures: The primary outcome was live birth per positive hCG. Subgroup analysis was performed by blastocyst biopsy day (days 5, 6, or 7). Poisson regression models were used to estimate stepwise comparisons between adjacent hCG groups; receiver operating characteristic analysis was performed to determine the predictive value of initial hCG level for live birth.

Results: A total of 6,410 single euploid embryo transfer cycles with initial positive serum hCG were included. Overall live birth after positive hCG was 71.0%. Higher initial hCG level increased live birth chance in a stepwise fashion, with lowest chance of live birth in group 1 (hCG 2.5 to <11) (1.6%), and highest in group 6 (hCG ≥100) (87.8%). Adjusted analysis demonstrated increasing probability of live birth between adjacent groups: group 2 vs. 1 aRR 6.76 [3.02–15.11], group 3 vs. 2 aRR 3.08 [2.27–4.19], group 4 vs. 3 aRR 1.80 [1.59–2.04], group 5 vs. 4 aRR 1.16 [1.08–1.25], and group 6 vs. 5 aRR 1.15 [1.10–1.21]. Live birth was similar across blastocyst biopsy subgroups, except in group 3 (25 to <50 mIU/mL), where day 5 blastocysts had the lowest live birth (28.8%) vs. days 6 and 7 blastocysts (42.7%, 41.9%). The area under the receiver operating characteristic curve was 0.83 (0.81–0.84), with an hCG of 75.7 mIU/mL representing the optimal threshold.

Conclusion: Initial serum hCG level after single euploid embryo transfer is a strong predictor of live birth, with a stepwise relationship between rising hCG thresholds. Findings from this study provide a valuable counseling tool for both physicians and patients utilizing single euploid embryo transfer.