After transfer to the uterus, the embryo must implant in the uterine lining and continue its development.  In order to do this it must break out of its “shell”.  This shell is called the zona pellucida.  Embryos may have a harder than normal shell or they may lack the energy needed to break out and complete the “hatching” process.  Embryologists can assist this hatching by make a small hole in the zona pellucida of the embryo on the third or fifth day of the embryo’s growth.  This is done through a specially fitted laser microscope.  The cells of the embryo can then escape from this hole and implant at an earlier time of development when the uterine lining may be more favorable.
Some embryos grown in the laboratory may have a harder shell than normal or may lack the energy requirements needed to complete the hatching process. The embryologists can help these embryos achieve successful implantation through a technique called assisted hatching.
On the third or fifth day of laboratory growth and shortly prior to uterine transfer, a small hole is made in the zona pellucida of the embryo with a specially fitted laser microscope. Through this opening, the cells of the embryo can escape from the shell and implant.

Patients who are most likely to benefit from assisted hatching are:

  • over 38 years of age
  • mildly elevated Day 3 FSH
  • multiple ART failures
  • Identified abnormalities with the zona pellucida.


How does assisted hatching work?

Before an embryo can attach to the wall of the womb, it has to break out or ‘hatch’ from its outer layer, the zona pellucida. It has been suggested that making a hole in, or thinning, this outer layer may help embryos to hatch, which may increase the chances of pregnancy.

Who Should Use Assisted Hatching with IVF?

Assisted hatching is thought to be helpful for couples with a poor prognosis whose embryos are thought to lack sufficient energy to complete the hatching process.

According to the American Society for Reproductive Medicine, assisted hatching may be indicated for women with:

  • Advanced maternal age (older than 38)
  • two or more failed IVF cycles
  • poor embryo quality

Will Assisted Hatching Increase the Chances of IVF Success?

Assisted hatching has been found to help with IVF success in poor prognosis patients.

There was an increase in implantation in all women studied, particularly in those over age 38 or those who had an elevated FSH level on Day 3 of the menstrual cycle. Couples with multiple failed IVF cycles also benefited from assisted hatching.

Because assisted hatching is a difficult technique, the success is dependent on the embryologist’s experience and technique, it is important to talk with your fertility clinic about how successful they are with the procedure.