Table 2.

Different studies comparing the slow preservation and/or vitrification of day 5 and day 6 blastocysts in terms of survival after warming, implantation and pregnancy rates

	Slowly frozen Day 5 Blastocysts	Slowly frozen Day 6 Blastocysts	Vitrified Day 5 Blastocysts	Vitrified Day 6 Blastocysts
Mukaida et al. 2003[9]			Survival 87%	Survival 55%
Stehlik et al. 2005[12]	Survival 83.1% Pregnancy rate 16.7%	Survival 89.5% Pregnancy rate 18.5%	Survival 100% Pregnancy rate 50%	Survival 100% Pregnancy rate 33%
Liebermann & Tucker 2006[13]	Survival 91.4% Implantation 29.6% Pregnancy rate 42.8%	Survival 94.8% Implantation 28.2% Pregnancy rate 43.1%	Survival 95.9% Implantation 33.4% Pregnancy 48.7%	Survival 97.5% Implantation 25.9% Pregnancy 42.8%
Kader et al. 2008[36]	DNA integrity index: 94.76% ± 4.70	DNA integrity index: 90.87% ± 6.16	DNA integrity index: 84.36% ± 8.76	DNA integrity index: 77.61% ± 16.65