Assisted hatching is the term used to describe the cutting or thinning of the human egg's outer shell (zona pellucida). Micropipettes are preferably used for the incision.
Laser beams may also be used (Laser assisted hatching). The embryo shell is thinned with the use of a biochemical method (special enzymes). This technique is usually applied in order to improve hatching and pregnancy rates of older women, whose rough-shelled eggs often make cell division and implantation more difficult. It is also used in IVF cases where previous pregnancy attempts have failed despite the perfect quality of the transferred eggs.