The most common reason for an IVF cycle to fail to produce a successful pregnancy is because the embryos don’t implant in the uterus. There are many reasons why this might happen, but most likely, it’s because of something related to the embryo. In some cases the embryo has difficulty breaking through its outer protein coating, called the zona pellucida, from which it must hatch before it can implant into the uterus. Assisted Hatching (AHA) is a procedure to help an embryo release from the zona pellucida.