In recent years, the extension of embryo culture up to the blastocyst stage (day 5) has increasingly gained ground. Most recent studies indicate that embryos reaching this stage have the highest implantation potential and can lead to high rates of pregnancy.
Approximately 50-60% of embryos generated in the laboratory reach the blastocyst stage. For embryos that fail to reach this stage, most have not developed fully, either because they have slow growth, or because they have already stopped their development at one of the previous stages. Therefore, embryo transfer on the 5th day may be used to select the most sustainable embryos.
Until now, the data indicates that this method is most favoured for couples:
• with relatively large numbers of embryos at their disposal,
• with multiple implantation failures in the past
• wishing to transfer only one embryo in order to avoid any risk of twin or multiple pregnancy
• where the female partner’s age is close to or above 40