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Updated: Jan 30, 2026

Protocol for Human Blastoids Modeling Blastocyst Development and Implantation
Published on: August 10, 2022
A comparison of morphokinetic markers predicting blastocyst formation and implantation potential from two large
N Zaninovic1, M Nohales2, Q Zhan3
1The Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY, USA. nizanin@med.cornell.edu.
Purpose:
To demonstrate whether the standard morphokinetic markers used for embryo selection have a similar relationship to blastocyst formation and implantation in two large clinical data sets.
Methods:
This is a retrospective cohort analysis striving to answer two distinct questions utilizing data sets from two large IVF clinics. Blastocysts (BL) and implanted blastocysts (I) in both clinics, IVI-Valencia (BL = 11,414, I = 479) and WMC (BL = 15,902; I = 337), were cultured in a time-lapse system (EmbryoScope, Vitrolife, Sweden). The study was designed to assess the relationship between early morphokinetic hallmarks and BL development, with a secondary analysis of implantation rates following single-embryo day 3 and day 5 transfers.
Results:
We performed a detailed graphical analysis for t3, t5, duration of the second cell cycle (cc2) (t3-t2), and the ratio (t5-t3)/(t5-t2). The t5 timing was not affected between the clinics. However, Weill Cornell Medicine's (WCM) proportions were significantly affected by having BL vs. not. A significant decrease of blastocysts with longer t5 in WCM data, while t5 was more informative in the IVI data set for the implantation rate.
Conclusions:
Morphokinetic intervals for early cleavages were distributed differently between the clinics. Incorporation of embryo-selection algorithms depends on the individual clinic's selected developmental hallmarks, all of which must be validated before incorporation into clinical practice.
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