Abnormal cleavage patterns in equine in vitro-produced embryos lead to higher early pregnancy loss.
Authors: Martin-Pelaez Soledad, de la Fuente Alejandro, Takahashi Kazuki, Monteiro Hugo, Mendes Mauricio, Meyers Stuart, Dini Pouya
Journal: Equine veterinary journal
Summary
# Cleavage Patterns as a Predictor of Success in Equine Embryo Transfer In vitro production of equine embryos remains hampered by higher early pregnancy loss rates compared to naturally conceived blastocysts, partly due to the lack of standardised assessment methods. Martin-Pelaez and colleagues used time-lapse imaging to examine the morphokinetic characteristics of 70 transferred embryos and 114 arrested embryos, focusing on abnormalities during the first mitotic division and the timing of blastocyst formation in relation to subsequent pregnancy outcomes. Embryos exhibiting abnormal cleavage patterns showed a dramatically higher early pregnancy loss rate of 53.3%, compared to just 22.6% in those with normal cleavage patterns, whilst faster blastocyst formation independently improved establishment of pregnancy at 14 days, though this advantage diminished after 25 days. These findings suggest that morphokinetic assessment—particularly evaluation of cleavage symmetry and timing—could serve as a practical classification tool for embryo selection before transfer, potentially helping reproductive specialists identify which in vitro embryos are most likely to establish viable pregnancies and reducing the current performance gap between in vivo and in vitro-derived embryos.
Read the full abstract on PubMed
Practical Takeaways
- •When selecting in vitro-produced embryos for transfer, prioritize those with normal cleavage patterns during early development to significantly reduce early pregnancy loss risk (from 53% to 23%)
- •Embryos that reach blastocyst stage earlier appear to have better pregnancy potential, suggesting developmental timing should be considered in embryo selection protocols
- •Implement morphokinetic assessment of cleavage patterns as a standardized classification tool to improve embryo selection and narrow the gap between in vitro and in vivo pregnancy success rates
Key Findings
- •Embryos with abnormal cleavage patterns showed 53.3% early pregnancy loss rate compared to 22.6% for normal cleavage patterns (p<0.05)
- •Earlier vitrification time (earlier blastocyst formation) increased odds of pregnancy at 14 days and decreased pregnancy loss until day 25
- •Abnormal cleavage patterns during first mitotic division decreased pregnancy odds and increased early pregnancy loss risk
- •Morphokinetic characteristics of first mitotic division can serve as embryo classification method to improve selection for transfer