Blastocyst development

The advantages of blastocyst transfer in mid-good responders include a reduction in multiple pregnancies due to single good-quality blastocyst transfer and an elevation of implantation and ongoing pregnancy rates due to establishment of the vitrification method. However, evidence is lacking as to whether blastocyst culture is effective in poor responders. In fact, few centers have adopted blastocyst transfer for all patients. Blastocyst development rate is around 50-60%. Several kinds of commercial sequential media are currently available and almost all Assisted Reproductive Technology (ART) units use these for treatment of patients. However, the period in which these media can be used is limited to 26-70 days according to the instructions provided by manufacturers. The half-life of pyruvate and antibiotics is supposedly short, and vitamins and hormones are unstable. Ideally, centers would make and use their own media within 72 h. In the near future, optimal ovarian stimulation, culture conditions, embryo transfer and luteal support should enable the possibility of providing healthy pregnancy following single blastocyst transfer in almost all patients.