An embryo is a ball of dozens of cells, some of which can contain chromosomal abnormalities. A large proportion of IVF embryos that are usually discarded due to some cells containing abnormalities have been found to result in successful pregnancies in the same manner as fully healthy embryos, potentially having a large impact on those undergoing IVF treatment.
Embryos containing a mixture of both healthy cells and cells with chromosomal abnormalities are called mosaic embryos and are rarely implanted during IVF treatment.
Antonio Capalbo and his team at Igenomix implanted embryos with different proportions of healthy and chromosomally abnormal cells finding that those with less than 50% abnormal cells (low-medium grade mosacism) resulted in the same rate of live births and miscarriages as embryos with no abnormalities.
484 healthy, 282 low-grade mosaic (20-30% abnormalities) and 131 medium-grade (30-50% abnormalities) mosaic embryos were implanted in a double-blind investigation.
38 newborns (27 from mosaic embryos) were followed up with genetic testing. Interestingly, there was no mosaicism present in any of the newborns developed from mosaic embryos. Capalbo points out genetic screening was conducted on a small sample size, however, the corresponding results are of high interest and importance.
As the percentage of fully unhealthy embryos (all cells possessing chromosomal abnormalities) depends on maternal age - around 30-40% for women in their 30s rising to 80% for women in their 40s - Capalbo’s findings could lead to higher chances of successful pregnancies for those having difficulty conceiving.
The researchers hope that their investigation will lead to discussions and changes in guidelines regarding clinical practice.
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