Embryo glue in IVF is a culture medium that contains hyaluronan, a natural substance found in the womb. Your embryo sits in this medium briefly before it is placed in the uterus.
Hyaluronan may help an embryo attach to the womb lining. Some trials suggest a small gain in live births, mainly for women using their own eggs.
The UK regulator, the HFEA, rates embryo glue amber. That means the evidence is unclear or conflicting. This article explains what that means in practice, who may benefit, and how to decide.
If you are weighing up add-ons before treatment, you can book a free fertility advisory call with our team. You can also read how our IVF treatment in London works from start to finish.
What Is Embryo Glue in IVF?
Embryo glue is an embryo transfer medium enriched with hyaluronan, also called hyaluronic acid (HA). It is the fluid your embryo is held in just before transfer. Standard media contain little or no HA.
The HFEA lists it as a treatment add-on. An add-on is an optional extra offered alongside standard IVF, often at extra cost. The regulator reviews the evidence for each one and publishes a traffic light rating. You can read its position on hyaluronate enriched pre transfer culture medium.
How Does Embryo Glue Work?
Embryo glue works by changing the fluid around the embryo for a short time before transfer. It does not alter the embryo itself. Here is the process in the lab and clinic:
-
Your embryo is grown in the lab until the day of transfer.
-
The embryologist moves it into the HA enriched medium.
-
It stays there briefly, so the medium surrounds it.
-
The embryo is loaded into the transfer catheter with a small amount of the same medium.
-
The doctor places it in the womb, usually under ultrasound guidance.
The possible mechanisms are not fully proven. Researchers suggest HA may help the embryo stick to the womb lining, may reduce uterine contractions that push embryos out, and may supply nutrients.
Does Embryo Glue Improve IVF Success?
Embryo glue may slightly raise live birth rates for women using their own eggs, but the strength of evidence is debated. The honest answer depends on which review you read.
| Source | What it found | Evidence quality |
|---|---|---|
| Heymann et al., 2022 (15 trials, 4,686 women) | Own egg cycles: live birth rose from 32% to 39% (RR 1.22) | Moderate |
| Heymann et al., 2022, donor egg cycles | Little effect on live birth (RR 1.12, not significant) | Low |
| University of Melbourne summary | About 3 more live births per 100 treatments, range from 0 fewer to 7 more | Low |
| Singh et al., 2015 (84 women) | 31% vs 23.8% pregnancy, not statistically significant | Small study |
The Heymann review is a systematic review, meaning it pools results from many trials. It calculated a number needed to treat of 14. In plain terms, about 14 women would need the medium for one extra live birth. You can read the full paper in Human Reproduction.
The University of Melbourne IVF service reaches a more cautious view. It reports low quality evidence and no clear effect on miscarriage. Its EmbryoGlue summary notes the medium has been used in more than 500,000 cycles worldwide since 2007.
A smaller trial published in 2015 did not find a significant difference overall. In a subgroup of women with repeated failed transfers, 6 of 12 became pregnant with embryo glue and none of 11 without it. The group was tiny, so this is a signal, not proof. See the Singh et al. study.
What the HFEA Amber Rating Means
Amber means the evidence is unclear or conflicting, and the add-on may not be effective for everyone. It is not a ban and not an endorsement. The HFEA reviewed the add-on through its expert advisory committee in 2023 and kept the amber rating.
In practice, this gives you a clear question to ask any clinic: what is the evidence for me, and what will it cost?
When Is Embryo Glue Used?
Clinics most often offer embryo glue at the time of embryo transfer in standard IVF or ICSI cycles. Some clinics use it for every patient. Others reserve it for particular situations.
Common reasons it is suggested:
-
A previous failed transfer with good quality embryos
-
Repeated implantation failure, meaning several transfers without a pregnancy
-
Unexplained infertility
-
Patients who want to use every available option
Because the evidence is mixed, a suggestion to use it should come with an explanation. It should not be presented as a guarantee.
Who Can Benefit From Embryo Glue?
The strongest signal is in women using their own eggs, particularly when a single embryo is transferred.
| Situation | Likely value of embryo glue |
|---|---|
| Own eggs, first transfer | Possible small gain, evidence moderate |
| Own eggs, repeated failed transfers | Possible gain, evidence limited |
| Donor egg cycles | Little effect shown |
| Patients wanting to avoid twins | Use only with single embryo transfer |
Age, embryo quality and womb health still matter far more. If embryo quality is the main concern, PGT A testing addresses a different question. For women in their forties, our guide on IVF over 40 covers what to consider.
Embryo Glue IVF Success Rate: What to Expect Realistically
An embryo glue IVF success rate depends mainly on your age and embryo quality, not on the medium. A rise from 32% to 39% is an average across trials. Your own chance may move by less, or not at all.
You can compare baseline results on our IVF success rates page.
Embryo Glue in IVF at IVF Matters
At IVF Matters, embryo transfer with embryo glue by Dr Irfana Koita is included in our IVF package. There is no separate add-on charge. You can see the current package details on our treatment prices page.
We include it openly while explaining the evidence, including the amber rating and the multiple pregnancy risk. Our approach to transfer is to favour single embryo transfer where suitable. You can read more about Dr Irfana Koita and our clinic at 10 Harley Street, London.
A Checklist for Your Clinic Conversation
Use these questions before agreeing to any add-on:
-
What is the HFEA rating for this add-on?
-
Is it included in my price or charged separately?
-
Is the evidence relevant to my age and egg source?
-
Will I have a single embryo transfer?
-
What does the clinic's own data show?
-
What happens if I decline it?
Frequently Asked Questions
Does embryo glue change how the transfer feels?
No. The doctor uses the same catheter and ultrasound guidance as a standard transfer. The only difference is the fluid your embryo is held in beforehand.
Does embryo glue change my embryo's genes?
No. The medium surrounds the embryo and does not alter its genetic code. It is a culture ingredient, not a genetic treatment.
Can embryo glue replace other steps such as PGT A?
No. They answer different questions. Embryo glue is about the transfer environment, while PGT A checks embryo chromosomes before transfer.
Should I ask about it before my first transfer?
It is reasonable to ask. A good clinic will explain the HFEA rating, the cost and whether it is relevant to your situation. You do not need to decide in the room on the day.
Is it the same as other IVF add-ons like endometrial scratching?
No. Endometrial scratching is a separate procedure on the womb lining. Embryo glue only changes the medium used for the embryo. Each add-on has its own HFEA rating.
Conclusion
Embryo glue in IVF is a low risk step with possible but uncertain benefit. The best evidence suggests a modest gain for women using their own eggs, balanced by a higher chance of twins unless one embryo is transferred. Donor egg cycles show little effect.
Ask for the evidence, ask for the price, and decide with your doctor. Ready to talk it through? Book a free fertility advisory call or book a private fertility consultation with IVF Matters.
Resources
-
HFEA: Hyaluronate enriched pre transfer culture medium (EmbryoGlue)
-
Heymann D et al., Human Reproduction, 2022: The effect of hyaluronic acid in embryo transfer media in donor oocyte and autologous oocyte cycles
-
University of Melbourne IVF: EmbryoGlue
-
Singh et al., 2015: Hyaluronan enriched transfer medium trial
Explore More
