Morphokinetic behavior in embryos leading to biochemical pregnancy.

Objective: It has been observed that faster developmental kinetics are linked with a higher number of embryo cells, improved blastocyst development, and increased rates of implantation and pregnancy. However, the embryonic morphokinetics' predictive value for biochemical pregnancy (BP) outcomes has been minimally investigated. The objective of this study was to investigate whether embryos leading to BP behave morphokinetically differently than those leading to positive or negative pregnancy result.

Methods: This case-control study performed in a private university-affiliated IVF center, included 1248 transferred embryos from 753 women undergoing ICSI cycles between March 2019 and April 2022. Patients were split into three groups according to the pregnancy outcome: Biochemical Group (n=30 cycles/54 transferred embryos), consisting of patients with a BP; Positive Group (n=255 cycles/444 transferred embryos), consisting of patients with a positive pregnancy result (clinical pregnancy); and Negative Group (n=468 cycles/750 transferred embryos), consisting of patients with a negative pregnancy result. Kinetic markers from the point of insemination were recorded in the EmbryoScope incubator.

Results: Embryos resulting in BP behaved similarly to those embryos resulting in a clinical pregnancy. Embryos resulting in a negative pregnancy showed significantly slower embryo development and KIDScore ranking compared to both Biochemical and Positive groups.

Conclusions: Embryos that resulted in a BP did not display evidence of abnormal morphokinetics on time-lapse imaging. Further research is needed to identify factors that can predict and prevent biochemical pregnancy.