Revisiting serum ß-hCG cut-off levels and pregnancy outcomes using single embryo transfer.

PURPOSE: The objective of this study is to identify the pregnancy outcomes based on day-16 ß-hCG level assessed with modern assays, in fresh single embryo transfers. METHODS: A retrospective cohort study at a single academic center between 2013 and 2017. A total of 1076 pregnancies were included. RESULTS: Pregnancies were divided into 10% groupings of 107-108 patients each. The 10 groups did not differ for baseline characteristics. There was no difference on outcomes based on cleavage or blastocyst transfer. At a serum ß-hCG level of 103 ± 13 (range 74-135), 50% had a biochemical loss. Biochemical pregnancy losses remained 21% at serum ß-hCG range (136-197). It was only once serum ß-hCG level reached 199-252 that the probability of a biochemical pregnancy loss was 12%. Interestingly, if a clinical pregnancy is present even at low day-16 serum ß-hCG levels, the likelihood of live birth is approximately 50%. This maximizes to 75% when the serum ß-hCG level was at least 253 IU/L. The relationship between serum day-16 ß-hCG levels and clinical pregnancy or live birth is quite strong with correlation coefficients above 0.8 which accounted for more than 75% of the variability in outcomes in both cases. Receiver operator curves determined that the cut-off for a clinical pregnancy was 190 and for live birth, it was 213 IU/L. CONCLUSION: An increase in the serum ß-hCG levels at which to expect a reassuring outcome is required based on modern assays, as compared with the old cut-off levels.

Blastocyst morphology has no relationship with serum ß-hCG levels and live birth rates once pregnant.

OBJECTIVE: What is the role of blastocyst morphology on day16 ß-hCG serum levels and pregnancy outcomes among patients who conceived through IVF cycles with single fresh Gardner's scored blastocyst transfers. STUDY DESIGN: A retrospective cohort study conducted at a single academic fertility center between January 2013 and December 2017. A total of 643 pregnancies were included in the study. RESULTS: The patients were divided into 5 groups according to Gardner's blastocysts grade of the ICM and the TE (grade), and into 4 groups according to blastocyst Gardner's degree of blastocoel expansion (stage). No significant differences were found between the different morphologic groups and day16 ß-hCG serum levels, clinical pregnancy rates and live births. A weak significant correlation was observed between Gardner's blastocysts grade and day 16 ß-hCG (Correlation Coefficient r= -0.098, p = .014) this correlation remained significant after controlling for confounders. (r= -0.099 p = . 013). A weak significant correlation was observed between Gardner's stage and day 16 ß-hCG (Correlation Coefficient r = 0.086, p = 0.029) this correlation lost significance after controlling for confounders. (r = 0.055, p = 0.340). When evaluating predictors of live birth using multivariate logistic regression, blastocyst grade (p = 0.33) and stage (p = 0.65), at transfer, were not associated with live births, when controlling for confounding effects. CONCLUSION: Once the patient conceives after IVF with single blastocyst, none of the morphological parameters have a strong impact on the day16 serum level of ß-hCG. Among women who conceived, blastocyst grade and stage were not associated with live births.