Implantation rate ( IR ) per embryo replaced and per embryo warmed were respectively 15.8 % ( 41/259 ) and 12.4 % ( 41/330 ) for Irvine , 17.0 % ( 40/235 ) and 12.1 % ( 40/330 ) for Vitrolife , 21.4 % ( 39/182 ) and 9.9 % ( 39/395 ) for slow-freezing ( NS ) .