To collapse or not to collapse blastocysts before vitrification? A matched case-control study on single vitrified-warmed blastocyst transfers

•Blastocyst collapsing is an invasive intervention and still not evidence based•This is the first matched case-control study analysing live births and neonatal outcome•Collapsing resulted in better survival and a non-significant 5% increase in live births•To confirm a 5% improvement, more than 2500 cases will be needed•No difference was found in neonatal outcomes