What an "add-on" is
An add-on is an optional technique offered in addition to standard fertility treatment, usually with the aim of improving the chance of a birth. Some are tests, some are laboratory techniques, some are medicines. Many are expensive, and the evidence behind them varies from weak to clearly negative.
Because patients cannot easily judge that evidence themselves, the Human Fertilisation and Embryology Authority (HFEA) publishes a rating for each common add-on (HFEA, Treatment add-ons). The page was last reviewed on 28 September 2026; the HFEA says ratings are reviewed when new evidence appears, and at least every five years.
The five colours
In October 2023 the HFEA replaced its earlier red, amber and green scheme with five colours:
- Green: high-quality evidence shows the add-on is effective at improving treatment outcomes.
- Yellow: it is not clear whether it is effective, because moderate or high-quality studies conflict.
- Grey: there is not enough moderate or high-quality evidence to say.
- Black: moderate or high-quality evidence shows it has no effect on treatment outcomes.
- Red: there are potential safety concerns, and/or evidence that it may reduce the effectiveness of treatment.
The key point comes first: no add-on on the HFEA's list is currently rated green.
The ratings
| Add-on | HFEA rating |
|---|---|
| Elective freeze-all cycles | Yellow |
| Endometrial scratching | Yellow |
| Hyaluronate-enriched transfer medium (e.g. EmbryoGlue) | Yellow |
| Androgen supplementation | Grey |
| Assisted hatching | Grey |
| Intralipids (immunological treatment) | Grey |
| IMSI (intracytoplasmic morphologic sperm injection) | Grey |
| Intrauterine culture | Grey |
| Microbiome testing | Grey |
| Sperm DNA fragmentation testing | Grey |
| PICSI (physiological ICSI) | Black |
| Time-lapse imaging and incubation | Black |
| Endometrial receptivity testing | Red |
| Intravenous immunoglobulin (IVIG) | Red |
| Steroids (glucocorticoids) as immunological treatment | Red |
| Platelet-rich plasma (PRP) | Red |
| Pre-implantation genetic testing for aneuploidy (PGT-A) | Red |
Source: HFEA treatment add-ons page, last reviewed 28 September 2026. Ratings refer to effectiveness at improving the chance of a birth for most patients; check the HFEA page for the details of each rating.
Reading a few of these ratings
Time-lapse imaging records embryos as they develop so that embryologists can choose which one to transfer. It is widely marketed, but the HFEA rates it black: the evidence shows no effect on the chance of a birth.
PGT-A tests embryos for an abnormal number of chromosomes. It is rated red for the general aim of improving birth rates. This is not the same thing as genetic testing for a specific inherited condition, which is a different procedure with a different purpose.
Endometrial scratching involves lightly scratching the lining of the womb before treatment. Studies conflict, which is why it is yellow rather than black or green.
Why ineffective add-ons are still offered
An add-on can look promising in a small or early study, then fail to show a benefit in larger, better-designed trials. Some techniques have reasonable uses in specific situations even if they do nothing for most patients. And some are simply profitable. The HFEA's ratings are designed to give patients a neutral starting point.
Questions to ask a clinic
- What is the HFEA rating for this add-on?
- What evidence is there that it helps someone in my situation, rather than patients in general?
- Does it have any risks, and what does it cost?
- What would you recommend if cost were not a factor?
The same habits help when reading any claim about fertility treatment: look for live birth as the outcome, and for randomised trials rather than single-clinic results. Our guide to reading a fertility study shows how, and IVF success rates explained sets out the baseline figures any add-on would need to improve.
This article summarises the regulator's published ratings. It is not medical advice: decisions about treatment should be made with your clinic.
A closer look at the yellow ratings
Three add-ons are currently rated yellow, meaning that good-quality studies disagree. Elective freeze-all means freezing every embryo instead of transferring one in the same cycle as egg collection. It can be the right choice for some patients, for example those at risk of over-responding to stimulation, but the evidence does not show that it improves the chance of a birth for everyone. Hyaluronate-enriched transfer media, such as EmbryoGlue, are culture solutions used at the moment of transfer; studies conflict on whether they help. Endometrial scratching, described above, is in the same position.
A yellow rating is not a recommendation. It means a patient considering the add-on should know that the question is open, and should weigh it against the cost.
Why some add-ons are red
A red rating goes further than "no benefit". It indicates potential safety concerns, or evidence that an add-on may reduce the effectiveness of treatment. Several immunological treatments, including intravenous immunoglobulin and steroids used for this purpose, are rated red, as are endometrial receptivity testing, platelet-rich plasma and PGT-A for the general aim of improving birth rates. Patients offered any of these should ask the clinic to explain why it is recommending it in their case.
Add-ons in context
The baseline matters. Standard IVF already has well-documented results that depend mainly on age, as set out in IVF success rates explained. The improvements that have made the biggest difference over the past decades, such as better freezing and single-embryo transfer, are now part of standard treatment rather than paid extras; the history is told in from one birth in 1978 to millions.
Paying for extras
Add-ons are usually charged on top of the cost of a cycle, and prices vary widely between clinics. Before agreeing to one, it is reasonable to ask for the price in writing, what it is expected to achieve, and how the clinic will judge whether it worked. A clinic that offers an add-on should be able to explain its HFEA rating and why it is being suggested for you in particular.