Early on in its formation, an embryo consists of a clump of cells protected by a shell layer called the zona pellucida. In order to stick to the womb and grow, the embryo needs to first ‘hatch’ from this shell.
In some cases, pregnancy could fail to occur because the embryo failed during hatching. It was for this purpose that Assisted Zona Hatching (AZH) is performed: very tiny holes in the zona pellucida are made using precise lasers on the third day of the embryo development, so that the blastocyst could hatch open from the zona pellucida.
On mothers above 35 years of age, mothers with increased FSH levels, or parents with a history of miscarriage, AZH is a recommended treatment. It can also help parents who decided to use their frozen embryo (blastocyst transfer), and especially to parents who discovered that their embryo has thicker than normal zona pellucida.
