Researchers in a 2020 study found that the transfer of a good quality and lower quality blastocyst resulted in an increased chance of live birth, mainly through an increase in the rate of multiples.
The transfer of a good quality blastocyst with a poor quality blastocyst could send mixed signals to the endometrium and could cause implantation to fail.
Hill et al. (2020) wanted to look at this in more detail.
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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Results
A good quality blastocyst was transferred alone to act as the control (single embryo transfer).
In the double embryo transfer, one good quality blastocyst and a second type of embryo was transferred (fair/poor quality blastocyst, early blastocyst, or morula). They compared this to the single embryo transfer control:
- When a fair/poor blastocyst was also transferred, the live birth rate increased (61% vs 49%) and so did the rate of multiples (27% vs 1%).
- When an early blastocyst was also transferred, the live birth rate increased (57% vs 49%) and so did the rate of multiples (22% vs 1%).
- When a morula was also transferred, the live birth rate didn’t increase, but the rate of multiples did (12% vs 1%).
The ASRM recommends transferring 1 embryo for good prognosis patients under the age of 38. So they looked at how the live birth rates changed with a double embryo transfer for those younger than 38, and those older than 38.
In patients younger than 38, transferring a second fair/poor quality blastocyst increased the live birth rate (57% vs 51% for single transfer), and the rate of multiples (19% vs 1%).
In patients older than 38, transferring a second fair/poor quality blastocyst increased the live birth rate (45% vs 33%) and the rate of multiples (15% vs 0%).
Conclusions
Double embryo transfers with a good quality embryo and a second lower quality embryo didn’t lower the chance of live birth, compared to the transfer of a single good quality embryo. This suggests that the endometrium does not discriminate against lower quality embryos in the presence of a good quality embryo.
The chance of live birth did increase from 1-12% with the double embryo transfer. However transferring two embryos didn’t increase the chance of having a singleton, but increased the chance of having multiples from 15-26%.
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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