To achieve this a small hole is made in the zona pellucida (mechanically, chemically or by laser) to facilitate hatching.
A systematic review and meta-analysis came to the result that assisted zona hatching is related to increased rates of clinical pregnancy and multiple pregnancy in women with previous repeated failure or frozen-thawed embryos.
[3] Sometimes, some embryos have a thickened or deformed zona pellucida that makes it difficult for them to come out and, therefore, can lead to implantation failures.
It is recommended in some cases: • Patients of advanced age (37 years or more) • Implantation failure • Anomalous zona pellucida (thick, partitioned,...) • Thawed embryos since vitrification produces a hardening of the zona pellucida.
• To do a blastocyst biopsy Those embryos biopsied to make PGD (preimplantation genetic diagnosis) will already have the hole made and, therefore, will hatch easily once they reach the stage of expanded blastocysts.