Time-Lapse Embryo Imaging: What the TILT Trial Found

An incubator with a built-in camera that photographs embryos continuously, so they can be assessed without being removed for inspection. Two claims are made for it: better selection from the extra data, and less disturbance to the embryos.

It is sold as a premium add-on in most clinics. The TILT trial was designed to separate those two claims, which is what makes it more informative than earlier studies.

• Continuous imaging inside the incubator.
• Claim one: better embryo selection from more data.
• Claim two: fewer disturbances because embryos are not removed.
• The two claims can be tested separately.

Separating them matters. If undisturbed culture is what helps, you do not need the imaging or the algorithm to get the benefit.

That time-lapse imaging did not significantly increase the odds of live birth compared with standard care. Live birth was 33.7% in the time-lapse arm and 33.0% in the control arm.

The third arm is the interesting one. Undisturbed culture — embryos left alone, without the imaging-based selection — produced 33.7% versus 36.6%, the numerically highest of the three.

• Time-lapse imaging: 33.7% live birth.
• Undisturbed culture: 36.6%.
• Standard care: 33.0%.
• No significant differences in any secondary outcome.

Read together, the arms suggest that whatever benefit exists lies in leaving embryos alone rather than in the imaging or the selection algorithm — and that even that difference did not reach significance.

TILT was double-blind and three-armed, which is unusual in this field and is what makes the result hard to argue with. Blinding matters because embryo selection involves judgement, and a clinician who knows which embryos were imaged cannot fully set that knowledge aside.

The three-arm structure is the more important innovation. A two-arm trial comparing time-lapse against standard care cannot tell you whether any difference came from the imaging, the algorithm, or simply from leaving the embryos alone — three things bundled into one intervention.

• Double-blind, which is uncommon in embryology trials.
• Three arms, separating imaging from undisturbed culture.
• 1,575 patients across two countries.
• Powered for live birth, not a surrogate outcome.

Powering for live birth rather than clinical pregnancy is worth noting separately. Many fertility studies report the easier outcome, which can move without any additional baby resulting.

Less than the marketing implied. A Cochrane review including 2,955 participants across nine trials reported no differences for any reproductive outcome, and rated the quality of evidence low to very low.

TILT has been described as the first adequately powered trial able to detect meaningful differences in live birth with time-lapse systems — which is a considerable statement about everything published before it.

• Cochrane: nine trials, 2,955 participants.
• No differences for any reproductive outcome.
• Evidence rated low to very low quality.
• TILT was the first adequately powered trial.

A technology in routine paid use for years before an adequately powered trial existed is the recurring story in this field, not an exception.

It is worth being precise about what 'low to very low quality' means in a Cochrane rating. It is not a comment on the honesty of the researchers — it describes risk of bias, imprecision and inconsistency across the studies pooled. A conclusion drawn from such evidence can be overturned by one good trial, which is exactly what happened.

That sequence is the useful thing to take from this. Nine trials and nearly 3,000 participants produced less certainty than one properly designed study of 1,575 — volume of evidence and quality of evidence are not the same measure.

That paying extra for time-lapse imaging is not supported by the best available trial. It does not mean the equipment is harmful or that a clinic using it is doing something wrong — many clinics use time-lapse incubators as standard at no additional charge.

• The charge is the issue, not the equipment.
• Ask whether it costs extra at your clinic.
• Ask what the clinic says about TILT specifically.
• Undisturbed culture is available without the imaging.

Our article on what the trials show across IVF add-ons sets this alongside the other add-ons that have been tested and found not to help.