Researchers in a 2022 study found that time-lapse technology using the GERI incubator improves implantation rates but not live birth rates or embryology outcomes compared to standard incubation techniques.
Time-lapse technology makes use of a incubator that takes pictures of embryos periodically and evaluates their development using an algorithm. It’s not clear if time-lapse is superior to conventional methods of culturing embryos and grading.
Zhang et al. (2022), in their multicenter randomized controlled trial (RCT) in China, compared pregnancy outcomes from 1,182 first-time IVF cycles using time-lapse embryo incubation or standard incubation between 2016 and 2019. The time-lapse system used was the Genea Embryo Review Incubator (GERI).
Embryos in the GERI incubator were left undisturbed until day 3, and were evaluated by the time-lapse software based on cleavage patterns, multinucleation status, etc. Embryos from the standard incubator were removed and checked daily and evaluated by standard grading methods.
Some important details about this study:
- Only good prognosis patients were recruited (<35 with at least 8 follicles on the day of trigger).
- One or two day 3 embryos were transferred (~93% of first time transfers were double embryo transfers).
- Both fresh and frozen transfers were performed.
- No differences in baseline characteristics (age, BMI, pregnancy history, etc.).
- Cumulative rates were included in this study and many of the women had a live birth or transferred all of their embryos (93.5%).
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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No improvement in embryology outcomes using time-lapse
They found no differences in the number of fertilized eggs or the number of top or poor quality embryos between the groups. Each group had about 5 transferrable embryos.
Implantation rate improved with time-lapse on first transfer, not cumulatively
In this study they compared implantation rates. This was defined as the number of fetal sacs with a heart beat (by ultrasound at 5-8 weeks) divided by the number of embryos transferred. So if 100 embryos were transferred to 80 women, and 50 fetal sacs with a heartbeat were detected, the implantation rate would be 50/100 = 50%.
After the first embryo transfer, women had a statistically significant improvement in implantation rate when they cultured their embryos with time-lapse, compared to those who didn’t (52.35% vs 47.11%). After adjustment for age, BMI, etc., this was still significant (adjusted relative risk [95% CI]: 1.11 [1.02-1.20]).
Women were allowed to transfer any extra embryos they had until 2021 (the study began in 2016) and cumulative rates were measured. There was no difference in cumulative implantation rates (50.69% vs 48.09%, adjusted relative risk [95% CI]: 1.06 [0.99-1.14]).
No improvements in live birth rates using time-lapse
This study found no difference in live birth rates between the time-lapse group and standard incubation group after the first transfer (63.24% vs 61.60%) or cumulatively (78.59% vs 78.76%).
Conclusions
In this study they found an improvement in implantation rates when using a time-lapse system compared to standard embryo incubation. This was after the first transfer only, and there was no improvement in cumulative implantation rates. They found no differences in live birth rates between the groups. There were also no differences in the number of top quality embryos between the groups.
A limitation of this study is that there are two differences between time-lapse and standard incubation that weren’t controlled for:
- The embryos cultured by time-lapse weren’t disturbed, while embryos in standard incubators were (they were checked daily).
- The time-lapse system uses an algorithm to select an embryo for transfer, while traditional embryo grading is used for embryos in standard incubation.
It’s possible that time-lapse embryos have a higher implantation rate because they weren’t disturbed or they were selected using the algorithm.
A previous study found no difference in outcomes when both groups were cultured in a time-lapse incubator, and then one group was removed and graded conventionally. This suggests that the algorithm had no impact (at least in this study).
The authors point out that the data from time-lapse studies is mostly inconclusive, as some studies find a benefit while others don’t. This may be due to how variable all the studies have been (good vs poor prognosis, culturing conditions, day 3 vs day 5, time-lapse systems, etc.). Because of this, it’s probably best to ask your clinic what their experience has been and go from there!
Reference
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About Embryoman
Embryoman (Sean Lauber) is a former embryologist and the founder of Remembryo, an IVF research and fertility education website. After working in an IVF lab in the US, he returned to Canada and now focuses on making fertility research more accessible. He holds a Master’s in Immunology and launched Remembryo in 2018 to help patients and professionals make sense of IVF research. Sean shares weekly study updates on Facebook, Instagram, and Reddit regularly. He also answers questions on Reddit or in his private Facebook group.
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