COMUNICACIONES PÓSTERS P-055 MALE EMBRYOS TAKE LONGER TO DEVELOP TO THE BLASTOCYSTS STAGE JJ Fraire Zamora, M Martínez, D García, R Vassena, A Rodríguez EUGIN - Barcelona (Barcelona) INTRODUCTION: OBJECTIVE: Differences in gene expression and metabolic uptake betweenTo compare morphokinetic parameters between male and female male and female preimplantation embryos have been found preimplantation embryos in order to determine any sex-specific in animal models and humans. These differences could affect developmental differences and avoid selection biases during the developmental timings of embryos resulting in differencesembryo transfers in ART clinics. in either sex. Morphokinetic parameters can precisely assess developmental timings.Only a few studies have analyzed MATERIAL AND METHOD: morphokinetic parameters between male and female preimplantation embryos and no consensus has been reached This study included retrospective time-lapse data (February 2018 to on whether there is any sex-specific difference. February 2020) from 102 preimplantation embryos giving rise to 51 baby boys and 51 baby girls, as seen at birth. This is a single-center 182 ASEBIR. Revista de Embriología Clínica y Biología de la Reproducción. Noviembre 2021 Vol. 26 Nº 2