Embryo Glue: What It Is and Whether the Evidence Supports It

Embryo glue is the marketing name for a transfer medium (EmbryoGlue is Vitrolife's brand; other manufacturers make similar products) containing elevated concentrations of hyaluronan, a naturally-occurring molecule present in the female reproductive tract at the time of implantation.

The theory: hyaluronan is thought to play a role in embryo-endometrial adhesion. Using a high-hyaluronan transfer medium might mimic this natural environment and improve implantation.

Unlike some IVF add-ons where the evidence has essentially collapsed, embryo glue has held up somewhat better in modern trials. But it's not the reliable pregnancy-rate booster that early marketing suggested.

What the Cochrane Reviews Show

Cochrane has periodically updated its review of adherence compounds (including hyaluronan) in embryo transfer media. The 2020 update analyzed data from 26 randomized trials involving over 6,000 patients. Rough findings:

• Clinical pregnancy rate: modest improvement with hyaluronan-enriched media, relative risk about 1.10–1.15
• Live birth rate: modest improvement, relative risk about 1.05–1.10 in most analyses
• Multiple pregnancy rate: also modestly increased (a mixed finding — reflects better implantation but adds risk if double transfer)

Translated to absolute terms: if baseline live birth rate is 30%, embryo glue might bring it to roughly 32–33%. That's a real effect, but not the transformative benefit some clinic marketing suggests.

Who Might Benefit Most

The evidence is stronger for some subgroups:

• Prior implantation failure: the strongest signal in subgroup analyses. Modest but consistent benefit.
• Fresh transfer cycles: slightly more evidence than for FET
• Blastocyst transfer: evidence roughly similar to day-3 transfer

Who Probably Doesn't Need It

• First-cycle patients with excellent embryos: baseline pregnancy probability is already high; incremental benefit is small
• Anyone with primary implantation problems from anatomical or receptivity issues: glue doesn't address root cause

Cost vs Benefit Framing

Embryo glue typically adds US$150–$500 to a transfer cost in the US, and often US$50–$180 in Colombia. It's inexpensive as add-ons go.

At those price points, the modest evidence-supported benefit makes the add-on defensible for patients with implantation history or those who want to optimize a single-transfer cycle. For a first fresh cycle in a young patient with good prognosis, the marginal benefit is likely too small to matter.

HFEA Traffic-Light Assessment

The UK's Human Fertilisation and Embryology Authority classifies embryo glue as amber (moderate evidence) — one of the higher ratings among IVF add-ons. Not the same as their black or red categories that flag ineffective add-ons.

What to Ask Your Clinic

1. "Do you use hyaluronan-enriched transfer media by default, or is it optional?"
2. "What's the additional cost?"
3. "Given my prior cycle history, what benefit do you expect?"

Some clinics use hyaluronan-enriched media as standard practice — no add-on charge, just their protocol. That's defensible given the evidence. Other clinics offer it as a premium add-on with dramatic marketing; the actual benefit is often overstated.

The Bottom Line

Embryo glue is one of the few IVF add-ons with genuine (if modest) randomized-trial support. It's not a game-changer. If your clinic uses it by default at no extra charge, that's fine. If it's being sold as a US$500 premium for your first IVF cycle, the marginal benefit probably doesn't justify the cost.