Does Severe Endometriosis have an Effect on Embryo Morphokinetic Parameters?

Endometriosis is one of the leading causes of infertility, affecting approximately one-third of women undergoing in vitro fertilization (IVF) treatment. Despite extensive research, the impact of endometriosis on embryo development remains controversial, particularly regarding its influence on both morphological and dynamic parameters. This retrospective comparative study analyzed 1,280 embryos cultured in a time-lapse incubator derived from 241 women under 38 years of age with a body mass index (BMI) below 30, whose partners did not present with severe male factor infertility. Of these, 729 embryos were obtained from patients with severe endometriosis (SE) and 551 from patients with tubal factor infertility (control group). All oocytes underwent intracytoplasmic morphologically selected sperm injection (IMSI). The abnormal fertilization rate was significantly higher in the SE group compared to the control group (4.9% vs. 2.7%, p = 0.022). No significant differences were observed in the time to pronuclear fading (tPNf), start of compaction (tSC), and expanded blastocyst formation (tEB) (p > 0.05). However, the durations of the first, second, and third embryonic cell cycles (ECC1, ECC2, and ECC3), as well as the synchronization of cell divisions (S2: t4–t3) and cleavage patterns (S3: t8–t5), were significantly different between the study groups (p < 0.05). Although most morphokinetic parameters were delayed in the SE group, the frequency of good-quality embryos on Days 3 and 5 and overall clinical outcomes were not significantly affected (p < 0.05). In conclusion, although embryos from patients with severe endometriosis exhibit significant delays in morphokinetic parameters, implantation and live birth outcomes remain comparable to those of controls when high-quality embryos are transferred.