Efficacy and safety of a one-step warming protocol of vitrified blastocyst stage embryos

Abstract

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%.