Effects of Different Trehalose Concentrations in a Warming Medium on Embryo Survival and Clinical Outcomes in Vitrified Human Embryos

<b><i>Background/Aims:</i></b> In the present study, we examined the effects of different concentrations of trehalose in a warming medium on both embryo survival and clinical outcomes in vitrified-warmed embryo transfer cycles. <b><i>Methods:</i></b> We retrospectively analyzed a total of 209 vitrified-warmed cycles from 177 patients who underwent in vitro fertilization or intracytoplasmic sperm injection and embryo transfer. Embryos were cryopreserved by the vitrification method and warmed in solutions containing either 0.5 or 1.0 <smlcap>M</smlcap> trehalose. We compared the 0.5 and 1.0 <smlcap>M</smlcap> trehalose warming solution groups with respect to the embryo survival rate after warming and clinical outcomes. <b><i>Results:</i></b> The embryo survival rate in the 1.0 <smlcap>M</smlcap> trehalose group (96.5%) was significantly higher than that in the 0.5 <smlcap>M</smlcap> trehalose group (57.0%). The percentage of embryo transfers after warming in the 1.0 <smlcap>M</smlcap> trehalose group (94.3%) was significantly higher than that in the 0.5 <smlcap>M</smlcap> trehalose group (83.7%). The clinical pregnancy rate in the 1.0 <smlcap>M</smlcap> trehalose group (25.0%) was significantly higher than that in the 0.5 <smlcap>M</smlcap> trehalose group (11.1%). <b><i>Conclusion:</i></b> Embryo survival and clinical pregnancy rates were higher when a 1.0 <smlcap>M</smlcap> trehalose solution was used than when a 0.5 <smlcap>M</smlcap> trehalose solution was used during the embryo warming process.