Assisted hatching is a procedure that helps the embryo break through the protective egg shell. It thus serves as a kind of hatching aid for the embryo. This modern procedure is performed as part of assisted reproduction, specifically “in vitro fertilization” (IVF) or “intracytoplasmic sperm injection” (ICSI).
Artificial insemination is not always successful—even if the egg has been successfully fertilized. This is sometimes because the resulting embryo has not managed to break free from its initial protective shell.
Only then can it implant itself in the uterine lining—which is essential for pregnancy.
Assisted hatching is a procedure that helps the embryo break through the protective egg shell. It is, in other words, a kind of hatching aid for the embryo.
The egg cell is surrounded by a flexible yet stable membrane made of glycoproteins. Medical professionals refer to it as the zona pellucida (Latin for “glass membrane”).
After the sperm penetrates the egg, the zona pellucida hardens, preventing additional sperm from entering the egg. It also protects the developing embryo from external influences.
Human egg cell with the surrounding zona pellucida; by Henry Vandyke Carter and Henry Gray (1918), *Anatomy of the Human Body* (see “Book” section below). Bartleby.com: *Gray’s Anatomy*, Plate 3, Public Domain, Link
Immediately after fertilization, the egg begins to divide. After 24 hours, a single cell has already developed into a four-cell embryo.
As development continues, the embryo develops into an 8-cell and then a 16-cell embryo. On the 4th day, the so-called morula forms, consisting of 32 tightly packed (compacted) cells.
Five days after fertilization, the embryo enters the implantation stage, known as the blastocyst stage. At this stage, the embryo consists of over 100 cells.
A fluid-filled cavity forms inside. Ready to implant into the uterine lining, the embryo now begins to emerge from its protective egg shell.
However, the egg shell has undergone changes or is so thick that the growing embryo has difficulty breaking through it. It’s similar to a chick that has trouble hatching from its eggshell.
This is where the problem begins. Because without hatching from the shell, the embryo cannot implant itself in the uterine lining. As a result, the embryo dies.
There are various techniques that help the embryo break out of the egg shell:
As a rule, fertility treatment consists of several treatment cycles. For only 28 percent of all women, the desire to have a child is fulfilled after the first treatment.
Assisted hatching is by no means a standard routine procedure. It is only used when a woman has already undergone several unsuccessful treatment cycles with IVF or ICSI.
Even with successful fertilization and embryo transfer, pregnancy may not occur if the embryo fails to hatch from its shell. It is then unable to implant. The reason is usually a shell that is too thick or has hardened.
These changes occur particularly frequently in women aged 37 and older. However, the phenomenon can also be observed in eggs that were previously frozen through cryopreservation.
The method of assisted hatching is not entirely uncontroversial. While various studies indicate that the procedure increases the chances of pregnancy,
However, there are still no conclusive long-term studies available. Based on current knowledge, assisted hatching does not affect the genetic material or the health of the future child.
However, it is not yet clear whether the method overcomes a natural implantation barrier in embryos with genetic defects.
Injury—and thus the loss of the embryo—cannot be ruled out either. Therefore, carefully weigh the risks and chances of success with your doctor before undergoing treatment.
Treatment with assisted hatching costs between 150 and 170 EUR per embryo. Since its success has not yet been sufficiently proven, neither public nor private health insurance plans cover the costs.
Despite all the doubts: For women who have undergone several previous attempts, assisted hatching can help them fulfill their dream of having a child.
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