The traffic lights, and the difference between grey, black and red
Not one add-on is rated green for improving your chance of a baby.
The UK fertility regulator publishes a rated list of add-ons. Its scientific advisory committee sets the ratings and reviews them when new evidence appears, and at least every five years. Since 2023 the system has used five categories, not three, and most descriptions of it still get that wrong.
| Rating | What it means, in the regulator's words |
|---|---|
| Green | High quality evidence shows this add-on is effective at improving the treatment outcome. |
| Yellow | It is not clear whether this add-on is effectivebecause the moderate to high quality evidence conflicts. |
| Grey | We cannot rate the effectivenessbecause there is insufficient moderate/high quality evidence. |
| Black | Moderate to high quality evidence shows this add-on has no effect on the treatment outcome. |
| Red | There are potential safety concernsand/or the evidence shows it may reduce treatment effectiveness. |
Current ratings for improving the chance of having a baby, for most patients:
| Add-on | Rating |
|---|---|
| Endometrial receptivity testing | Red |
| PGT-A embryo screening | Red (green for reducing miscarriage) |
| Immunological, IVIG | Red |
| Immunological, steroids | Red |
| Platelet-rich plasma | Red |
| Time-lapse imaging and incubation | Black |
| Physiological ICSI in male-factor cycles | Black |
| Elective freeze-all cycles | Yellow |
| Endometrial scratching | Yellow |
| Hyaluronate-enriched transfer medium | Yellow |
| Assisted hatching, androgens, intralipids, IMSI, intrauterine culture | Grey |
The single most useful sentence a fertility patient can be givenNot one add-on on that list is rated green for improving the chance of having a baby.
Researchers interviewed 73 patients, clinicians and embryologists about the ratings. Patients were surprised that no add-on is green for improving the chance of a baby, and questioned what a traffic light system is worth when that light never turns green. The five-category revision exists because the old three-colour version lumped "no evidence" together with "evidence of harm", and patients said those meant very different things to them.
Researchers interviewed 73 patients, clinicians and embryologists about the ratings. Patients were surprised that no add-on is green for improving the chance of a baby, and questioned what a traffic light system is worth when that light never turns green. The five-category revision exists because the old three-colour version lumped "no evidence" together with "evidence of harm", and patients said those meant very different things to them.
The regulator's own advice on money is quoted in full in the cost topic at the end of this part. In short: think about whether more cycles of IVF or insemination would buy you more than one cycle loaded with add-ons that have not been shown to work.
Where this comes from:
84. Human Fertilisation and Embryology Authority. Treatment add-ons with limited evidence. London: HFEA; published October 16, 2023, last reviewed February 26, 2026.
129. Lensen S, Armstrong S, Vaughan E, Caughey L, Peate M, Farquhar C, et al. "It all depends on why it's red": qualitative interviews exploring patient and professional views of a traffic light system for IVF add-ons. Reprod Fertil. 2023;4(2):e220136.
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This page is educational. It supports the conversation with your own clinicians. It is not consent to any treatment, and it cannot assess you. If you are worried about a symptom now, see urgent warning signs.