Purpose: To investigate whether embryo shape is a useful morphologic predictor of developmental competence in IVF cycles.
Methods: Two hundred eighteen day 3 single embryo transfer (SET) cycles and 225 day 3 double embryo transfer (DET) cycles in which only 8-cell non-fragmented embryos with symmetric blastomeres were transferred and in which the developmental fate of each embryo was known were analyzed for IVF outcomes with respect to embryo shape. Embryo shape was quantitatively calculated after digitizing embryo images using MATLAB, where a score of 1.0 represented a perfectly circular embryo.
Results: The SET data did not reveal a significant impact of embryo shape on embryo developmental fate. The DET data revealed a trend toward the best outcomes in cycles where both embryos exhibited "roundness" scores in the highest tertiles (T3) for embryo shape. However only one subgroup (T2/T1-one embryo in the middle shape tertile (T2) and one in the lowest shape tertile (T1)) was associated with significantly lower odds of live-birth as compared to the referent group (T3/T3). When SET and DET data were combined, embryo shape was not found to be a predictor of IVF outcome.
Conclusions: Based on this retrospective analysis, the weak association of day 3 embryo shape with implantation potential suggests that this morphological characteristic is unlikely to be a useful additional marker for embryo selection after cell number, fragmentation, and blastomere symmetry. Further studies are planned to assess applicability of these conclusions to embryos of varying stages and grades.