Despite successful fertilization of the egg cells during in vitro fertilization or after a microinjection (ICSI), the desired pregnancy does not occur in some cases.

One possible reason for this may be that the embryo cannot slip out of its shell to settle in the uterus. The embryo shell naturally opens around five days after the embryo is fertilized. If the embryo does not hatch or only hatches incompletely, implantation cannot take place in the uterus. The reasons for this can be a noticeably thick envelope around the embryo or cryopreservation in the pronuclear stage.

A new procedure in reproductive medicine, "laser hatching", supports the hatching of the embryo. With this new technique, we can use a fine laser beam to open a small area in the outer shell of the embryo under microscopic control.