Researchers in a 2024 study found no health problems in children born from mosaic embryo transfers, with an average age of 3 years. They also found no differences in obstetric outcomes between mosaic and euploid transfers.
PGT-A can be used to determine which embryos have the right number of chromosomes (euploids) or the wrong number (aneuploid). Mosaics are embryos that have a mix of euploid and aneuploid cells and can have intermediate success rates.
There isn’t much data on the health of children born after mosaic embryo transfers, and a new study wanted to fill in this gap. They also compared perinatal and neonatal outcomes for mosaic embryo transfers compared to euploid transfers.
Check my complete guide to mosaic embryos to learn more about mosaics, or my complete guide to PGT-A to get more background on PGT-A (aka PGS testing).
🔗 Original studies are referenced in this post or within the linked Remembryo posts.
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This study compared obstetric outcomes for children born from mosaic or euploid transfers. There were 115 euploid and 57 mosaic births.
The mosaics were low-level, and had <50% aneuploid cells:
- 61.4% had 25-39% mosaicism and 38.6% had 40-50% mosaicism.
- 82.5% had one chromosome affected and 17.5% had two chromosomes affected.
For euploid vs mosaic transfers, there were no differences in any of these obstetric outcomes:
- Pregnancy complications (diabetes gravidaris, hypertension, hypothyroidism, premature rupture of membranes).
- Delivery complications (instrumentalized childbirth, umbilical cord problems, meconium aspiration syndrome, abnormal fetal monitoring).
- Caesarian section.
- Gestational age (preterm births, very preterm births).
- Newborn measures (birth weight, birth length, birth head circumference, Apgar score).
- Neonatal admission rates.
- Congenital anomalies.
- Hospital admission (surgical intervention, medical hospitalization).
The average age of children in this study was 3.48 years (euploid) and 2.92 years (mosaic). There were no differences in the rates of chronic diseases between the children, and there were no health problems reported.
They did prenatal screening in about half of the patients who had a mosaic transfer (27 patients: 23 non-invasive test and 4 amniocentesis), and all the results were normal. They also did a karyotype on 6 of the mosaic children, which were all normal (ie. mosaicism was not detected in these children).
Although this was a small study, it provides reassuring data for people transferring mosaic embryos. They found no differences in obstetric outcomes for those transferring euploid or mosaic embryos. This agrees with another (larger) study that found no differences in neonatal outcomes compared to euploids. This larger study found that 5.6% of prenatal tests were abnormal, many of which were unrelated to the original mosaic PGT-A result, with 3 (1.2%) having the same mosaic result. You can read more about this study in my post Miscarriage and neonatal outcomes for over 2,000 mosaic embryo transfers. This suggests that most mosaic embryos self-correct, or have mosaicism that isn’t detected, while 1.2% remain mosaic (which wasn’t detected in the current study, probably due to the small sample size).
If you liked this post, I suggest you check out my post Can a mosaic embryo result in a normal baby?, where I’ve combined a lot of information about the health of mosaic embryo births.
References
They also submitted an abstract during the 39th Hybrid Annual Meeting of the European Society of Human Reproduction and Embryology that has some additional information included here.
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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.
Related posts:
ASRM’s 2024 committee opinion on the use of PGT-A
Depletion of aneuploid cells in mosaic embryos
PGDIS releases 2021 guidelines for mosaic embryo transfers
Does a PGT-A biopsy match the rest of the embryo?
Can a mosaic embryo result in a normal baby?
A look at how PGT-A results change with age, using data from over 86,000 biopsies
More sensitive PGT-A test shows that nearly all blastocysts, fetal tissues are mosaic
A third of mosaics retest as aneuploid with different PGT-A test