Embryo Selection for Single Embryo Transfer on Day 3 Based on Combination of Cleavage Patterns and Timing Parameters in in Vitro Fertilization Patients

OBJECTIVE:To evaluate whether the selection of embryos based on the combination of cleavage patterns and timing parameters using time-lapse imaging could improve the pregnancy outcomes of single embryo transfer (SET) on day 3. STUDY DESIGN: A total of 1,728 normally fertilized and cleaved embryos were included to establish the selection criteria by using time-lapse imaging (TLI). The association of embryo cleavage patterns, timing parameters, and blastocyst quality was evaluated. Another 150 SET cycles were included in a prospective study to validate the selection criteria. RESULTS: Embryos with normal cleavage, uneven cleavage, and nonaxial cleavage had relatively high rates of good-quality blastocysts. In addition, we identified s2 (<= 0.50 h) and t5 (<= 49.07 h) as the most predictive timing parameters. The strategy based on the combination of embryo cleavage patterns and timing parameters resulted in a higher good quality blastocyst rate of 68.8%. In a prospective study, 150 SET cycles were carried out to validate the established algorithm. The clinical pregnancy rate in elective SET cycles using TLI was higher than that of SET using static morphological evaluation (75.0% vs. 47.30%). CONCLUSION: The hierarchical strategy based on the combination of embryo cleavage patterns and timing parameters is effective for selecting the optimal embryo.