Noninferiority randomized controlled trial comparing embryo development using media developed for sequential or undisturbed culture in a time lapse setup

In this randomized sibling study we found no differences in blastocyst development between sequential and single-step media.


Thorir Hardarson, Ph.D., Mona Bungum, Ph.D., Joe Conaghan, Ph.D., Marius Meintjes, Ph.D., Samuel J. Chantilis, M.D., Laszlo Molnar, Ph.D., Kristina Gunnarsson, M.Sc., Matts Wikland, Ph.D.

Volume 104, Issue 6, Pages 1452-1459



To study whether a culture medium that allows undisturbed culture supports human embryo development to the blastocyst stage equivalently to a well-established sequential media.


Prospective, randomized, double-blinded sibling trial.


Independent in vitro fertilization (IVF) clinics.


One hundred twenty-eight patients, with 1,356 zygotes randomized into two study arms.


Embryos randomly allocated into two study arms to compare embryo development on a time-lapse system using a single-step medium or sequential media.

Main Outcome Measure(s):

Percentage of good-quality blastocysts on day 5.


Percentage of day-5 good-quality blastocysts was 21.1% (standard deviation [SD] ±21.6%) and 22.3% (SD ±22.1%) in the single-step time-lapse medium (G-TL) and the sequential media (G-1/G-2) groups, respectively. The mean difference (−1.2; 95% CI, −6.0; 3.6) between the two media systems for the primary end point was less than the noninferiority margin of −8%. There was a statistically significantly lower number of good-quality embryos on day 3 in the G-TL group [50.7% (SD ±30.6%) vs. 60.8% (SD ±30.7%)]. Four out of the 11 measured morphokinetic parameters were statistically significantly different for the two media used. The mean levels of ammonium concentration in the media at the end of the culture period was statistically significantly lower in the G-TL group as compared with the G-2 group.


We have shown that a single-step culture medium supports blastocyst development equivalently to established sequential media. The ammonium concentrations were lower in the single-step media, and the measured morphokinetic parameters were modified somewhat.

Clinical Trial Registration Number:


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