Is there a relationship between morphokinetic parameters and neonatal sex in fresh embryo transfers?

To investigate whether morphokinetic parameters differ between male and female embryos in IVF embryos resulting in live births, a retrospective cohort study was undertaken. Files of all live births resulting from a single embryo transfer (SET) cultured in time-lapse incubators between 2013 and 2019 in two tertiary care centres were reviewed. The study group consisted of 187 SETs resulted in 187 live births, of which 100 were females (53.5%) and 87 were males (46.5%). Embryo selection for transfer was based on the known implantation data (KID) score provided by the Embryoscope and morphological assessment by experienced embryologists. Neonatal sex was confirmed through live birth documentation. Morphokinetic parameters and day 3 and day 5 KID scores of male and female embryos were compared. Maternal baseline and treatment characteristics were similar between groups. Morphokinetic time-lapse parameters of male and female embryos including: pronuclei fading; cleavage timings (t2-t9); second and third cell cycle durations; synchrony of the second and third cleavages; late morphokinetic parameters and KID scores did not differ between groups. In conclusion, time-lapse morphokinetic parameters and embryo selection methods do not seem to differ between male and female embryos, and their utilization does not bias towards any neonatal sex.