P–232 A trophectoderm morphology can predict a live birth rate and gender imbalance

Abstract Study question Which morphology parameter is the most predictable in the live birth rate and can affect the sex ratio? Summary answer The trophectoderm grade (TE) can predict the live birth rate and skewed to male gender after single vitrified-warmed blastocyst transfers (SVBT). What is known already The Gardner and Schoolcraft grading system of blastocyst evaluation with morphology is the major predictor of the clinical outcome in ART. Inner cell mass (ICM) and trophectoderm (TE) morphology are strongly correlated between clinical pregnancy, live birth, and miscarriage. A greater degree of expansion of the transferred blastocysts showed a higher implantation rate. Therefore, it is essential to clarify which parameter is more predictable in clinical outcome during elective SVBT. However, SVBT has some potential limitations, including adverse effects such as a male-biased imbalance in the sex ratio. Study design, size, duration The retrospective analysis used 1138 cycles of SVBT in the Ojinmed IVF center, Mongolia, between May 2015 to January 2019. The morphology grade and blastocyst inner diameter compared with clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage. The sex ratio was estimated for all patients, excluding those who underwent PGT-A, donor oocytes, and monozygotic twins. Blastocyst quality was evaluated with Gardner and Schoolcraft grading system and measured inner diameter of the blastocyst. Participants/materials, setting, methods All patients underwent a clomiphene-based minimal ovarian stimulation protocol or drug-free natural cycle IVF treatment. On day 5 to 6, blastocysts that reached an inner diameter >160μm were immediately vitrified. Blastocyst morphology evaluated by ICM and TE grade. The CPR (with a confirmed gestational sac at 6–7 weeks of pregnancy) and the LBR (live birth at 22 weeks of pregnancy over) were estimated per embryo transfer procedure, followed by miscarriage rate. Main results and the role of chance The CPR was 44.69%, 38.97%, and 25.91% for A, B, C grades of ICM, respectively. And the LBR was 39.82%, 34.62%, and 19.1% for A, B, C grades of ICM, respectively. TE was strongly related to CPR (aOR=2.47, 95% CI 1.71–3.58, p