Biological relevance of trophectoderm morphology: initial β-hCG measurements correlate with trophectoderm grading on euploid frozen embryo transfers

Objective: To analyze the correlation between TE grading and initial β-hCG serum level after single euploid embryo transfer. Secondarily, to explore the association between TE grading with subsequent IVF outcomes. Design: Retrospective cohort analysis. Setting: Single, academic, private infertility and assisted reproductive care institute. Patients or other participants: Infertility patients who underwent a single euploid embryo transfer that resulted in a positive pregnancy test. Intervention(s): β-hCG measurements. Main outcome measure(s): Correlation between TE grade with first β-hCG measurement. Second outcome measurements included ongoing pregnancy, biochemical pregnancy loss, and clinical pregnancy loss rates. Results: 2,798 cases were analyzed. A significant difference in initial β-hCG measurement among groups (TE A: median 143.4 mIU/mL IQR 79.2–211.2; TE B: 119 mIU/mL IQR 57.1–177.8; TE C: 82.4 mIU/mL IQR 36.3–136.4, p ≤ 0.0001) was observed. There was a significant correlation found between the TE grade and β-hCG measurements (p ≤ 0.0001, r² = 0.10). TE grade was not associated with higher odds of biochemical pregnancy loss (TE A vs. TE B: aOR 1.01 CI95% 0.97–1.05; TE A vs. TE C: aOR 1.03 CI95% 0.98–1.08), or higher odds of clinical pregnancy loss (TE A vs. TE B: aOR 1.02 CI95% 0.98–1.05; TE A vs. TE C: aOR 1.03 CI95% 0.98–1.07). Conclusions: In patients with euploid embryos, TE grade correlates with the first pregnancy test measurement of β-hCG. We propose this finding helps to appoint a relevant link between morphology assessment and early embryo development in vivo.