Human chorionic gonadotropin levels are equally predictive for pregnancy outcome after fresh and vitrified-warmed blastocyst transfer.

PURPOSE: The aim of the present study was to evaluate if the live birth predictive values of β-hCG levels differ in fresh and vitrified-warmed blastocyst transfer cycles.

METHODS

In the retrospectively designed study, 775 cycles with positive β-hCG values 13 days after fresh blastocyst transfer (fresh ET; n = 568) or vitrified-warmed blastocyst transfer (FET; n = 207) were selected for analysis. Average β-hCG levels stratified according to pregnancy outcome (biochemical pregnancy, spontaneous abortion, ectopic pregnancy, and singleton or twin birth) were compared between fresh ET and FET cycles. To determine the optimal sensitivity and specificity of β-hCG levels for live birth prediction, a ROC curve was constructed. Fisher's exact test was used to compare the positive predictive values (PPV).

RESULTS

Average β-hCG levels stratified according to pregnancy outcome were not statistically different between fresh ET and FET cycles. In fresh ET and in FET group, the β-hCG levels were significantly higher in pregnancies resulting in live birth compared to non-viable pregnancies (1,035 vs. 462 IU/L, p < 0.001 and 968 vs. 411 IU/L, p < 0.001). Optimal cut-off level for live birth prediction was 495 IU/L (sensitivity 83.0 %, specificity 71.8 %) after ET and 527 IU/L (sensitivity 80.0 % and specificity 76.6 %) after FET. The PPV for live birth rate in the groups after ET and FET were 90.6 % and 84.9 % respectively, without statistically significant difference (p > 0.05).

CONCLUSION

Beta-hCG levels after fresh and vitrified-warmed blastocyst transfer are equally predictive for pregnancy outcome. Clinicians can be encouraged to interpret β-hCG results in the same manner.