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Assisted hatching

Treatment add-on with limited evidence

For most patients, having a routine cycle of proven fertility treatment is effective without using any treatment add-ons.


Assisted hatching is rated red because there is no evidence from randomised controlled trials (RCTs) to show that it is effective at improving the chances of having a baby for most fertility patients. 

What does this traffic light rating mean?

Our traffic-light rated list of add-ons consists of three colours that indicate whether the evidence, in the form of high-quality RCTs, shows that a treatment add-on is effective at improving the chances of having a baby for most fertility patients.  

We give a red symbol for an add-on where there is no evidence from RCTs to show that it is effective at improving your chances of having a baby for most fertility patients.

The January 2019 consensus statement (PDF) between the HFEA and ten other professional and patient bodies agreed that treatments that have no strong evidence of their safety and/or effectiveness should only be offered in a research setting. Patients should not be charged extra to take part in research, including clinical trials.

For specific patient groups there may be reasons for the use of a treatment add-on other than improving your chances of having a baby. In these situations, it may be appropriate for you to be offered a treatment add-on as part of your treatment and not in a research setting.

Our traffic light ratings only indicate the effectiveness of a treatment add-on at improving your chances of having a baby. Specific safety concerns about a treatment add-on are included under the dedicated section ‘Is this treatment add-on safe?’

What is assisted hatching?

The egg and early embryo are surrounded by a thick layer of special proteins called the zona pellucida. Before an embryo can implant in the womb it has to break out or ‘hatch’ from its zona pellucida. Some people think that assisted hatching - using acid, lasers or other tools to thin or make a hole in the zona pellucida - helps the embryo to ‘hatch’.

What’s the evidence for assisted hatching?

The National Institute for Clinical Excellence (NICE) is the national body advising doctors on treatments. It says:

“Assisted hatching is not recommended because it has not been shown to improve pregnancy rates.”

NICE also says that further research is needed to find out whether assisted hatching influences birth rates and to examine the consequences for children born as a result of this procedure.

Some clinics believe assisted hatching can lead to higher birth rates in specific subgroups of patients. There is however no high-quality evidence to support the use of assisted hatching for any patient.

At the October 2019 Scientific and Clinical Advances Advisory Committee (SCAAC) meeting the Committee evaluated the evidence base for assisted hatching. Minutes of this discussion and the evidence used to inform this discussion are available on the SCAAC webpage.

Is this treatment add-on safe?

Assisted hatching does not carry any known additional risks for the person undergoing fertility treatment. However, there is always some risk of damaging embryos with these types of procedures.

If you have any questions about the safety and risks, your clinic will be able to discuss whether a treatment add-on would be safe for you to use considering your specific medical history and circumstances.

What are treatment add-ons?

  • optional additional treatments, also referred to as ‘supplementary’, ‘adjuvants’ or ‘embryology treatments’.
  • often claim to be effective at improving the chances of having a baby (live birth rate) but the evidence to support this for most fertility patients is usually missing or not very reliable.
  • likely to involve an additional cost on top of the cost of a routine cycle of proven fertility treatment. Some treatment add-ons can cost hundreds or thousands of pounds each.

It is important to keep in mind that for most patients, having routine cycles of proven fertility treatment are effective without using any treatment add-ons. If you are paying directly for your own treatment, you may want to think about whether it might be more effective and/or affordable to pay for multiple routine proven treatment cycles, rather than spending large sums of money on a single treatment cycle with treatment add-ons that haven’t been proven to be effective at increasing the likelihood of you having a baby.

We aim to publish clear and reliable information about some of the treatment add-ons that don’t have enough evidence, from high-quality randomised control trials (RCTs), to show that they are effective at improving your chances of having a baby.

To make it easier to understand the scientific evidence for each treatment add-on we have developed our traffic-light rated list of add-ons.

Review date: 4 January 2024