19/02/2026
“You have beautiful embryos.” She heard this before every transfer. And every transfer failed.
Embryo grading is a visual assessment. It evaluates appearance: cell symmetry, fragmentation, blastocyst expansion, inner cell mass, and trophectoderm quality. It is predictive on a population level, but inter-clinic reliability is only fair to moderate (2,5). It does not see chromosomal status (unless PGT-A is performed) and does not guarantee implantation (1,3).
A “perfect” looking embryo can still be chromosomally abnormal, and may also harbor other cellular problems not visible under a microscope (1,4,6).
Even PGT-A, which screens for chromosome number, has published limitations. A Cochrane review and large RCTS show mixed results on whether PGT-A improves cumulative live birth rates for all populations (1,4,6).
Mosaicism, biopsy accuracy, and self-correction potential remain active areas of research.
When a quality embryo fails to implant, the answer is rarely “bad luck.” Even after confirmed euploid transfer, about 30% of chromosomally normal blastocysts do not lead to live birth (7). Endometrial factors are underexplored. Chronic endometritis is found in approximately 14-36% of women with recurrent implantation failure (14,15,16). Displaced implantation windows, low progesterone, and uterine pathology are each associated with impaired outcomes and can be assessed and addressed (9,10, 11, 12,13, 18,19).
Yet at many clinics, the response to a failed transfer of a good embryo is: “We will try again.” Without new investigation. Without addressing what the embryo was transferred into.
A failed transfer of a quality embryo is not a diagnosis. It is an invitation to investigate everything else.
78.8% of my patients take home healthy babies. This is our clinic’s internal outcome data. Because we investigate the whole picture, not just the embryo.