A blastocyst is a day5/6 embryo. With appropriate media and proper lab conditions, the embryos can be cultured in IVF lab up to 5 to 6 days. It is believed that the embryos which have survived in the artificial conditions for 5-6days and have made it through the key growth process offer a greater chance of successful implantation and pregnancy. Blastocyst culture thus helps in better embryo selection.

One of the biggest challenges in IVF practise is to select the embryo which can maximise the chances of conception. Traditionally multiple numbers of embryos (2 or 3) have been transferred to the womb to enhance the success rates. However, this practice carries an inherent risk of multiple pregnancies.
Blastocyst culture allows for a better selection of embryo to be transferred. Such selection enhances the chances of implantation and successful pregnancy without the risk of multiple pregnancies and its associated complications such as prematurity, IUGR and foetal loss.

However, blastocyst culture is not suitable and feasible for all patients. This technique is not useful when fewer embryos are formed as in such cases additional culture may not improve the pregnancy rates. Therefore, the pros and cons of the blastocyst culture are kept in mind and individualised decision according to the case is made.