Time-lapse parameters as predictors of blastocyst development and pregnancy outcome in embryos from good prognosis patients: a prospective cohort study.

STUDY QUESTION: Do early time-lapse parameters predict which embryos will develop to high-quality blastocysts and does timing of development differ between embryos that implant and those that do not.

SUMMARY ANSWER: Development to high-quality blastocysts could be predicted within the first 48 h of culture, whereas time-lapse parameters could not predict pregnancy.

WHAT IS KNOWN ALREADY: Historical cohort studies on embryos from unselected groups of patients have suggested several putative kinetic markers of viability. Before well-designed randomized studies can be conducted, relevant selection models based on solid data must be developed. So far conclusions from the previous studies are ambiguous.

STUDY DESIGN, SIZE, DURATION: A prospective cohort study conducted from February 2011 to June 2012. A total of 571 ICSI embryos from 92 patients were included in the blastocyst development analysis and 84 single embryo transfers were included in the pregnancy outcome analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS: Embryos from women aged <38 years, with no endometriosis and ≥ 8 oocytes retrieved. University affiliated clinic. Embryos were cultured in a time-lapse incubator till Day 6. Logistic regression analysis was performed with variables selected based on indication.

MAIN RESULTS AND THE ROLE OF CHANCE: Duration of the first cytokinesis, duration of the 3-cell stage and direct cleavage to 3-cells predicted development to high-quality blastocyst. We found no difference in timing between implanted and non-implanted embryos.

LIMITATIONS, REASONS FOR CAUTION: A larger study might detect differences in timing between implanted and non-implanted embryos. The cohort consisted of good prognosis patients only and may not be representative of the entire IVF population.

WIDER IMPLICATIONS OF THE FINDINGS: Our results in context with the lack of consistency in previous studies and the presumed influences of different external factors indicate that a universal algorithm for optimal timing of development might not be feasible. The apparent negative significance of division patterns that differ from the expected may imply that time-lapse will facilitate de-selection of embryos.

STUDY FUNDING/COMPETING INTEREST(S): Funding for the present study was provided by Aarhus University, the Lippert Foundation, the Toyota Foundation, the Aase og Einar Danielsen foundation and by an unrestricted grant from MSD and Ferring. The authors declare no conflict of interest.

TRIAL REGISTRATION NUMBER: The study was registered at ClinicalTrial.gov with accession number NCT01139268.