What Does Assisted Hatching (AHA) Mean in IVF?

By BSc, MSc (embryologist), BSc, MSc (embryologist) and BA, MA (fertility counselor).
Last Update: 05/30/2014

Assisted hatching (AHA) is a procedure which consists of performing a small hole in the zona pellucida (ZP) (membrane surrounding the plasma membrane of the embryo).

Its aim is to enable the inner cell mass (ICM) of the embryo to break through the ZP when the embryo is at blastocyst stage so that it can implant into the maternal uterus.

The different sections of this article have been assembled into the following table of contents.

Zona pellucida of embryos

In a natural manner, the embryo's zona pellucida gradually becomes thinner. On day 6, the embryo becomes detached from the ZP in order to adhere to the endometrium and, therefore, implant into it.

There are some eggs with thickened zona pellucida, which may make it difficult for the embryo to break through and implant. These embryos have, thus, fewer chances for implantation and continue its development.

Performing this technique may increase the chances for implantation of these embryos. Assisted hatching can be made during an in vitro fertilisation or ICSI cycle, although it will raise the price of the whole process.


  • Eggs with thickened ZP
  • Embryo transfer after thawing
  • Women older than 37 with problems to become pregnant
  • High levels of basal serum FSH
  • Repeated IVF cycles failure
  • Slow embryonic growth
  • Embryos with an abnormal colour of the ZP
  • Embryos with a high cleavage rate


Generally speaking, we can conclude that this technique increases the embryo's implantation rate.

Nevertheless, importance should be given to the fact that the results may be very variable, since, depending on the assisted reproduction clinic, the success rate may vary greatly. This imbalance is due to the complexity of the technique and the expertise that the whole process requires.

Another important point that should be explained is that, if this technique is not used in those cases where it is indicated, it may not have any advantage.

FAQs from users

What is Assisted Hatching?

By Patricia Recuerda Tomás BSc, MSc (embryologist).

Assisted Hatching (AH) is an assisted reproduction technique that can be used in the IVF lab with the resulting embryos. AH involves the penetration of the zona pellucida that recovers the embryos using a laser. It is performed on day 3 of embryo development.

AH allows the blastocyst to leave the zona pellucida, thereby increasing the implantation potential of embryos. Given that it is an invasive technique that carries some risks, it is indicated in the following cases only: patients who are 37 or over, embryos with a thick, dark or abnormal zona pellucida, multinuclear embryos, previous implantation failure, developmentally delayed cleavage-stage embryos, too high FSH levels, poor responders.

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Authors and contributors

 Laura Garrido
Laura Garrido
BSc, MSc
Bachelor's Degree in Biotechnology from the Pablo de Olavide University (UPO) of Seville, Spain. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI). Experience at IVF, andrology, and general analysis laboratories. Embryologist specialized in Assisted Reproduction. More information about Laura Garrido
 Patricia Recuerda Tomás
Patricia Recuerda Tomás
BSc, MSc
Bachelor's Degree in Biology from the University of Alcalá de Henares. Master’s Degree about the Theoretical Basis and Laboratory Procedures in Assisted Reproduction from the University of Valencia (UV). Extensive experience working at several Assisted Reproduction laboratories. More information about Patricia Recuerda Tomás
License: 19882M
Adapted into english by:
 Sandra Fernández
Sandra Fernández
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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