The researchers looked at using a process called vitrification instead of slow-freezing to preserve embryos and blastocysts in fertility treatments. They studied 253 treatment cycles over 6 years to compare how well each method worked. They found that vitrification had higher success rates than slow-freezing. When using vitrification, more embryos and blastocysts survived the freezing and thawing process. Additionally, there were higher pregnancy and delivery rates with vitrification compared to slow-freezing. Vitrification was especially beneficial for blastocysts, significantly increasing the chances of implantation and live births. This study shows that using vitrification can lead to better outcomes in fertility treatments compared to slow-freezing.