Alice Tubbing1, Chloë Shaw-Jackson2, Lieveke Ameye3, Jérôme Colin1, Serge Rozenberg1, Candice Autin1. 1. Department of Gynaecology, CHU St-Pierre (Université Libre de Bruxelles), Rue Haute 322, 1000, Brussels, Belgium. 2. Department of Gynaecology, CHU St-Pierre (Université Libre de Bruxelles), Rue Haute 322, 1000, Brussels, Belgium. Chloe_shaw-jackson@stpierre-bru.be. 3. Data Centre, Jules Bordet Institute (Université Libre de Bruxelles), Rue Hégèr Bordet 1, 1000, Brussels, Belgium.
Abstract
PURPOSE: An investigation into the clinical implications of delayed blastulation (day 5 versus day 6) was carried out for cryo cycles, as heterogeneous results persist in the current literature. METHODS: We performed a retrospective study comparing clinical pregnancies and live births between 178 blastocysts vitrified and warmed on day 5 versus 149 on day 6. The stage of blastocyst development was taken into account and adjustment for confounding factors was performed. RESULTS: Our results demonstrate a significant difference in clinical pregnancy (43 versus 23% p value < 0.001) and live birth rates (34 versus 16% p value < 0.001) regarding the day of vitrification, in favour of day 5. This difference persisted after adjustment for confounding factors. The adjusted odds ratio for clinical pregnancies and deliveries for the day 5 group compared to that of the day 6 group was 2.83 (95%CI, 1.48 to 5.41) and 2.94 (95%CI, 1.39 to 6.22), respectively. When the stage of development of the blastocyst was taken into consideration, we still observed a significant advantage of day 5 versus day 6 vitrification. CONCLUSIONS: Day of vitrification (day 5 versus day 6) appears to be an independent predictor of clinical outcomes. Stratification of our cohort was carried out according to the developmental stage, and significant differences persisted. Although the transfer of day 6 cryopreserved embryos remains a viable option, giving priority to a day 5 embryo would reduce the time to pregnancy.
PURPOSE: An investigation into the clinical implications of delayed blastulation (day 5 versus day 6) was carried out for cryo cycles, as heterogeneous results persist in the current literature. METHODS: We performed a retrospective study comparing clinical pregnancies and live births between 178 blastocysts vitrified and warmed on day 5 versus 149 on day 6. The stage of blastocyst development was taken into account and adjustment for confounding factors was performed. RESULTS: Our results demonstrate a significant difference in clinical pregnancy (43 versus 23% p value < 0.001) and live birth rates (34 versus 16% p value < 0.001) regarding the day of vitrification, in favour of day 5. This difference persisted after adjustment for confounding factors. The adjusted odds ratio for clinical pregnancies and deliveries for the day 5 group compared to that of the day 6 group was 2.83 (95%CI, 1.48 to 5.41) and 2.94 (95%CI, 1.39 to 6.22), respectively. When the stage of development of the blastocyst was taken into consideration, we still observed a significant advantage of day 5 versus day 6 vitrification. CONCLUSIONS: Day of vitrification (day 5 versus day 6) appears to be an independent predictor of clinical outcomes. Stratification of our cohort was carried out according to the developmental stage, and significant differences persisted. Although the transfer of day 6 cryopreserved embryos remains a viable option, giving priority to a day 5 embryo would reduce the time to pregnancy.
Entities:
Keywords:
Assisted reproduction; Blastocyst; Day 5; Day 6; Live births; Vitrification
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