Morphologic grading of euploid blastocysts influences implantation and ongoing pregnancy rates.

OBJECTIVE: To determine whether blastocyst grading can predict pregnancy outcomes in the frozen-thawed embryo transfer (FET) of euploid blastocysts.

DESIGN: Retrospective cohort study.

SETTING: Academic medical center.

PATIENT(S): Women who underwent FET of euploid embryo(s) between January 2013 and December 2015, with blastocysts were divided into four groups based on their morphologic grading before cryopreservation: excellent (≥3AA), good (3-6AB, 3-6BA, 1-2AA), average (3-6BB, 3-6AC, 3-6CA, 1-2AB, 1-2BA), and poor (1-6BC, 1-6CB, 1-6CC, 1-2BB).

INTERVENTION(S): FET.

MAIN OUTCOMES MEASURE(S): Ongoing pregnancy rate (OPR).

RESULT(S): A total of 417 FET cycles (477 embryos) were included. Excellent-quality embryos (n = 38) yielded a statistically significantly higher OPR than poor-quality embryos (n = 106) (84.2% vs. 35.8%; adjusted odds ratio 11.0; 95% confidence interval, 3.8-32.1) and average-quality embryos (n = 197) (84.2% vs. 55.8%; adjusted odds ratio 4.8; 95% confidence interval, 1.7-13.3). Good-quality embryos (n = 76) were associated with a statistically significantly higher OPR than poor-quality embryos (61.8% vs. 35.8%). These odds ratios were adjusted for patient's age, body mass index, number of transferred embryos, type of frozen cycle, peak endometrial thickness, day of trophectoderm biopsy (5 or 6), and total number of euploid embryos for each patient. An inner cell mass grade of A yielded a statistically significantly higher OPR than ICM grade C (76.2% vs. 13.5%) or grade B (76.2% vs. 53.6%) after controlling for all confounders.

CONCLUSION(S): Contrary to prior published studies, the current data suggest that blastocyst morphologic grading and particularly inner cell mass grade is a useful predictor of OPR per euploid embryo. Morphologic grading should be used to help in the selection among euploid blastocysts.