The term refers to the hatching spontaneous opening of the zona pellucida (shell which is the embryo) with subsequent expulsion of the embryo at the blastocyst stage. This phenomenon should occur so that the embryo can be implanted in the endometrium (lining of the uterus internal). It is believed that one of the possible mechanisms that lead to a reduced rate of implantation in assisted reproduction procedures, would be a difficulty in the process of hatching naturally. Thus, we assisted hatching in the laboratory, using the laser to specific embryos before transferring them to the uterus, in order to try to increase the chances of implantation and pregnancy. This technique is identified when an increase in the thickness of the zona pellucida, when there is unexplained failure of implantation in previous cycles of IVF, in women aged more than 37 years and in cases of transfer of frozen embryos.