Can Advanced Paternal Age Increase Chromosomally Abnormal Embryos?
Men’s bodies are constantly making new sperm cells but can advanced paternal age increase chromosomally abnormal embryos? In a large study published in the July 2020 journal Fertility and Sterility, no association of increased chromosomal abnormalities in embryos from men with advanced age was found. In this study of 3118 embryos derived from 407 male patients and women less than 34 years of age, there was no difference in the percentage of embryos with chromosomal abnormalities in men less than 40 years old, 40 to 49 years old, and 50 years or older.
In the study, all groups showed that 70% of the embryos were chromosomally normal, 13.9% were chromosomally abnormal and 16.1% were found to be chromosomally mosaic. The same percentage of abnormal embryos was seen in all groups of men whether aged less than 40, aged 40-49, or those over 50 years of age. In fact careful study of the men over age 50 did not show an increased rate of chromosomally abnormal embryos with increasing age. Even in the men over 55 and the few men over 60, the embryos did not show any increased risk of chromosomally abnormal embryos.
Of note, all the eggs were fertilized with ICSI and all the embryos were tested at the blastocyst stage after 5-6 days of growth. 16 % of the embryos were mosaic which means a certain portion of the cells were normal and some of the cells were abnormal. In general, these embryos are not suitable for transfer.
As has been shown in previous studies, the men in the over 50 group had slightly lower sperm volume and motility but an increased sperm count; the fertilization rate was found to be very slightly lower in the older men, but there was no difference in embryo growth to the blastocyst stage among the groups.
The egg quality in this study was very well controlled by only using eggs form young egg donors aged 19-33. Interestingly, even in these young female donors, there was an increased number abnormal embryos with increasing age. This largest study of embryos which answered can advanced paternal age increase chromosomally abnormal embryos is reassuring as there was no increase risk of abnormal embryos with increasing age.
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