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Updated: Jun 23, 2026
Morphometric Protocol for the Objective Assessment of Blastocyst Behavior During Vitrification and Warming Steps
Published on: February 28, 2019
Efficacy and safety of a one-step warming protocol of vitrified blastocyst stage embryos
Emma R Ebinger1, Helena Misurac2, Alexa M Giovannini3
1Embryology Department, Adora Fertility, Taringa, Queensland, Australia.
Objective:
To study the effect of a one-step warming technique on survival and clinical outcomes of vitrified-warmed blastocysts in a consecutive cohort of patients.
Design:
Retrospective consecutive cohort study.
Subjects:
This study included 1,303 transferred embryos from 950 unique patients treated at three clinics.
Exposure:
The exposure group included embryos warmed using a one-step warming protocol with a 1M sucrose solution for 1 min. The control group included embryos warmed using traditional, multistep warming, where embryos were exposed to 1M sucrose for 1 min, followed by 3 min in 0.5M sucrose, and 10 mins in washing solutions.
Main Outcome Measures:
The goal of this study was to compare survival, clinical pregnancy rate (CPR), ongoing pregnancy rate (OPR), and live birth rate (LBR) between multi- and one-step warming techniques. Additionally, subgroup analyses by maternal age, embryo morphology, day of vitrification, and mode of fertilization were also performed.
Results:
Survival rates were comparable across all comparisons. Pregnancy rates were comparable between multistep and one-step groups (CPR: 43.2% vs. 44.4%; OPR: 34.3% vs. 37.9%; LBR: 34.0% vs. 35.6%). Pregnancy probabilities between warming techniques were comparable between groups at any age point (32 - CPR: 42.6% vs. 47.4%; OPR: 34.9% vs. 39.6%; 42 - CPR: 25.8% vs. 20.7%; OPR: 12.6% vs. 12.9%). Good quality embryos (G2) had a lower chance of pregnancy than top quality embryos (G1) overall, but pregnancy rates were similar between groups (G1 - CPR: 52.2% vs. 55.9%; OPR: 45.7% vs. 49.2%; G2 - CPR: 39.0% vs. 39.4%; OPR: 29.2% vs. 33%). Similarly, Day 6 embryos were less likely to achieve pregnancy than Day 5 embryos, but pregnancy rates were comparable between groups (D5 - CPR: 45.5% vs. 46.5%; OPR: 36.3% vs. 40.2%; D6 - CPR: 27.3% vs. 27.6%; OPR: 18.2% vs. 22.4%). Pregnancy rates between intracytoplasmic sperm injection (ICSI) for male factor infertility and in vitro fertilization (IVF) were again comparable between groups (ICSI - CPR: 42.3% vs. 40.7%; OPR: 35.6% vs. 34.5%; IVF - CPR: 45.7% vs. 46.8%; OPR: 35.5% vs. 41.5%).
Conclusion:
One-step embryo warming provides similar survival and pregnancy outcomes compared with classical multistep warming while decreasing the procedure time by more than 90%.
