Background: Currently, the effect of laser-assisted hatching (LAH) on the outcome of cryopreserved embryo remains controversial and unclear, especially on the cryopreserved embryos using a novel vitrification method.

Objective: To compare the pregnancy outcomes of vitrified-warmed cleavage stage embryos transfer using LAH breaching or LAH thinning versus those not using LAH.

Materials and Methods: Sixty patients with vitrified-warmed cleavage embryo transfer were randomly assigned to a control group without LAH treatment, LAH-breeching group, and LAH-thinning group. The outcome measurements were clinical pregnancy rate, implantation rate, and live birth rate.

Results: The clinical pregnancy rate (35% versus 20% versus 25%) and implantation rate (17.3% versus 11.5% versus 11.3%) were lower in both LAH-breaching and LAH-thinning group than the control group, but not statistically significant (p>0.05). The live birth rate (30% versus 5% versus 5%) was significantly lower in both the LAH-breaching and LAH-thinning group than the control group (p=0.026).

Conclusion: LAH regardless of breaching or thinning methods significantly decreases live birth rate in vitrified-warmed cleavage-stage embryo transfer.