Investigation of the effects of trophectoderm morphology on obstetric outcomes in fifth day blastocyst transfer in patients undergoing in-vitro-fertilization

Objective: Trophectoderm (TE) cells are the first differentiating cells in embryo development and have epithelial features. TE cells, which associate with implantation of the blastocyst into the uterine endometrium, contribute to the formation of the placenta. Inner cells mass (ICM) together with TE cells are used for determining embryo quality. The aim of this study was to investigate the role of TE and ICM cells on pregnancy outcome in 5th day blastocyst transferred in-vitro-fertilization (IVF) pregnancy. Material and Methods: This was a retrospective study using data from all patients who applied for blastocyst transfer IVF between January 2015 and March 2019 at the Reproductive Endocrinology and Infertility Center of Akdeniz University Faculty of Medicine, Department of Obstetrics and Gynecology. ALPHA Istanbul consensus evaluation system was used for grading of the blastocyst. The embryo quality, expansion, ICM and TE morphology of the 5th day transferred blastocyst was assessed, together with abortion rate, live birth rate, pregnancy complications, and pregnancy outcomes. Results: There was a significantly increased risk of preeclampsia (PE) (7.8% vs 1.1%; p=0.041), preterm delivery (PD) (36% vs 17.7%; p=0.037), and antenatal bleeding rates (13.6% vs 5%; p=0.021) in TE-C compared to the TE-A + TE-B blastocysts. Furthermore, a higher rate of obstetric complications was observed in ICM-C compared to ICM-A and B (p=0.003). There was a significant correlation between TE morphology and implantation success, ongoing pregnancy rate, and abortion incidence. Conclusion: These results suggest that TE cell morphology is related to implantation success and pregnancy outcomes, especially in terms of the risk of abortion, PE, PD, and antenatal bleeding. It may be advisable to counsel women concerning possible poor obstetric outcome due to poor ICM quality. Future prospective and controlled studies are needed to clarify this association.