Influence of parental age on chromosomal abnormalities in PGT-A embryos: exponentially increasing in the mother and completely null in the father.

Purpose: To study the influence of parental age on aneuploidy rates (AR) in PGT-A cycles and on the recurrence rate.

Methods: A total of 16,029 PGT-A cycles were studied over a 9-year period. The median age was 40.0 [37.0; 41.0] in women and 40.0 [37.0; 43.0] in men. In 48.3%, the biopsy was performed on day 3 embryos (D3E) and in 51.7% on blastocysts (79.5% using NGS).

Results: In women, the AR was almost constant at < 50% until the age of 35 but increased steadily to reach > 90% at 44. The AR pattern varied according to embryo stage and was considerably higher in D3E, with a steeper curve. A U-pattern was observed in D3E, whereas this was not seen in blastocysts. In the blastocysts analyzed using NGS, trisomy 21 increased sixfold (from < 1% at < 30 to nearly 5% in women aged 40), whereas trisomies 13 and 18 increased their frequency twofold. After 3 biopsied blastocysts studied using NGS, 100% of women aged ≤ 30 had at least 1 euploid embryo, vs 96% aged 31-35, almost 80% aged 36-40, 50% aged 41-45, and 33% aged 46-50. In terms of the man's age, the non-adjusted analysis revealed a correlation with AR. However, after correcting for the woman's age, no correlation was observed. The man's age was not associated with any of the aneuploidies potentially resulting in a newborn.

Conclusions: Carrying out PGT-A systematically in IVF cycles from the age of 38-39 is highly recommended. Advanced paternal age does not carry an increased risk of aneuploidy for the embryo and does not in itself constitute an indication for PGT-A.