Table 1.

Basic information of the included studies comparing open versus closed vitrification on oocytes and embryos

Authors, Country (Year)	Study period	Study type	Participant	No. of cycles and oocytes/embryos thawed		Outcomes	Funding	Overall quality assessment
				Study (Closed)	Control (Open)
Kuwayama et al. (2005), Japan	NM	Prospective	Embryo	88 embryos	227 embryos	CsR; CPR; LBR	None declared	Moderate risk
Chen et al. (2013), China	2010.04–2012.05	Retrospective	Embryo	226 cycles; 308 embryos	106 cycles; 150 embryos	CsR; IR; CaR; CPR; OPR; MR; LBR; BB; MR	Yes	Low risk
Panagiotidis et al. (2013), Greece	2009.06–2011.09	Prospective	Embryo	224 cycles; 513 embryos	208 cycles; 492 embryos	CsR; PβR; IR; CaR; CPR; OPR; MR; LBR; BB; MR	None declared	Low risk
Desai et al. (2013), America	2011.01–2012.08	Retrospective	Embryo	95 cycles; 184 embryos	161 cycles; 302 embryos	CsR; IR; CaR; CPR; OPR; MR; LBR; BB; MR	None declared	Low risk
Hashimoto et al. (2013), Japan	2011.07–2012.09	Prospective	Embryo	100 embryos	163 embryos	CsR; IR; OPR	Yes	Moderate risk
Roy et al., Australia (2014)	NM	Prospective	Embryo	23 embryos	13 embryos	CsR; OPR	Yes	Serious risk
Iwahata et al. (2015), Japan	2011.11–2013.12	Retrospective	Embryo	302 cycles; 313 embryos	539 cycles; 561 embryos	CsR; IR; CPR; MR; LBR; MR	None declared	Low risk
Paffoni et al. (2011), Italy	2007.06–2009.04	Retrospective	Oocyte/embryo	51 cycles; 261 MII oocytes/87 embryos	53 cycles; 268 MII oocytes/116 embryos	CsR; IR; FR; ClR; GQER; CPR; LBR	None declared	Low risk
Papatheodorou et al. (2013), Greece	2007.02–2010.12	Prospective	Oocyte	598 MII oocytes	608 MII oocytes	CsR; FR; ClR; GQER; PβR; IR; CPR; MR; OPR; LBR	None declared	Low risk
De Munck et al. (2016), Belgium	2014.01–2015.07	Prospective	Oocyte/embryo	253 MII oocytes	257 MII oocytes	CsR; FR; GQER; PβR; MR; OPR	No funding	Low risk
Gook et al. (2016), Australia	2012.06–2015.06	Prospective	Oocyte	39 MII oocytes	79 MII oocytes	CsR	None declared	Serious risk
Sarandi et al. (2016), France	2014.11–2015.05	Prospective	Oocyte	96 GV/MI oocytes	118 GV/MI oocytes	CsR	None declared	Serious risk

Notes: The ROBINS-I tool was used for quality assessment of observational studies. BB babies born per transferred blastocysts, CaR cancellation rate, CBS Cryo Bio System, ClR cleavage rate, CPR clinical pregnancy rate, CsR cryosurvival rate, FR fertilization rate, GQER good quality embryo rate, HSV high security straws, IR implantation rate, LBR: live birth rate, MBR multiple birth rate, MR miscarriage rate, NM not mentioned, OPR ongoing pregnancy rate, PβR positive βHCG rate