Table 1.

Characteristic of included studies

Study	Year	Source	Patientor population	Method of data collection	Risk of bias	Outcomes	NOS scoring
Chambers, et al. (2015) [6]	2009 to 2012	National registry	47370 live deliveries in Australia and New Zealand (day 2/3 vs day 5/6)	Australian and New Zealand Assisted Reproduction Database	Some patients do not have complete information	No increased risk of LBW and PTB resulting from blastocyst transfers compared to cleavage transfers	8
Dar, et al. (2013) [24]	2001 to 2009	National registry	12712 singletons in Canada on a voluntary basis (day 3 vs day 5/6)	Canadian ART Register database	The PTB unadjusted by potential confoundding factors. The women in the blastocyst group were young	Increased risk of preterm birth with day 5/6 transfers	8
Fernando, et al. (2012) [22]	2004 to 2009	Single center	4202 women conceived via IVF/ICSI in Australia (day 2/3/4 vs day 5/6)	Monash IVF patient database	Cleavage stage includes day 4.	No statistically significant difference between transfers on days 5/6 and days 2/3/4 in all maternal and perinatal outcomes	7
Ginstrom Ernstad, et al. (2016) [13]	2002 to 2013	National registry	30566 singletons in Sweden via IVF/ICSI treatments (day 2/3 vs day 5/6)	Swedish Medical Birth Register and the National Patient Register	The number of blastocyst transfers is very low relative to the number of cleavage-stage transfers	Singletons born after blastocyst transfer had a lower risk of LBW and SGA as compared to cleavage-stage transfers.	8
Kalra, et al. (2012) [20]	2004 to 2006	National registry	69039 live deliveries via IVF in U.S. (day 3 vs day5/6)	Society of Assisted Reproductive Technologies database	Women in the blastocyst transfer group were young. No ICSI cycles in the study.	After blastocyst transfers, patients were at an increased risk for PTB and VTPB as compared with cleavage-stage transfer	9
Martin, et al. (2012) [19]	2002 to 2009	Single center	1183 singltons from the hospital of Tours, France (day 2 vs day 5/6)	Forms completed by couples	Forms filled out by couples.	Incresded risk of PTB after blastocyst transfer	7
Oron, et al. (2014) [15].	December 2008 to December 2012	Single center	1543 single embryo transfers in McGill University Health Center, Canada (day 2/3 vs day 5)	In their computerized database	The small number of live births resulting from cleavage and blastocyst embryo transfers.	No increased risk of maternal or neonatal complications in pregnancies resulting from blastocyst embryo transfers	8
Maxwell, et al. (2015) [25]	2003 to 2012	Single center	392 singleton live births via IVF/ICSI at New York University Fertility Center (day 3 vs day 5/6)	In their computerized database	Women were young in the blastocyst group.	No increased risk of PTB and VPTB	8
Zhu, et al. (2014) [21]	January 2009 to June 2012	Single center	2929 singletons born at Peking University Third Hospital (day 3 vs day 5/6)	In their computerized database	The number of day 3 transfers was high relative to the number of day 5/6 transfers. No ICSI cycles in the study	No increased risk of SGA	8
Ishihara, et al. (2014) [23]	2008 to 2010	National registry	277042 singletons born in Japan	Japanese ART registry database collected by the Japan Society of Obstetrics and Gynecology	Women were young in the blastocyst transfer group.	Blastocyst transfers were associated with a significantly decreased rate of SGA	8
De Vos, et al. (2015) [27]	April 2004 to December 2009	Single center	2098 singleton live births in single center, Belgium (day 3 vs day 5)	In their computerized database	Women were young in the blastocyst group.	The mean singleton birthweights were not different between day 3 embryo transfers and day 5 blastocyst transfers	8
Makinen, et al. (2012)	2000 to 2010	Single center	1079 infants born after treatment at the Family Federation of Finland Fertility Clinic in Helsinki, Finland (day 2/3 vs day 5/6)	In their computerized database	Details about patients were not clearly described.	No increased risk of SGA	7