~35% aneuploidy at age 31–34
At ages 31 to 34, approximately one-third of blastocysts are aneuploid; the rate climbs to 40% by 35, 60% by 38, and over 80% by age 42.
Snapshot · The Peter Attia Drive
#397 ‒ Endometriosis and adenomyosis: diagnosis, fertility, reproductive aging, and emerging treatments | Renato Tomioka, M.D., Ph.D.
Explore episode
Jun 22, 2026
Where this was said
Endometriosis and fertility: the roles of age, embryo quality, IVF, and surgery
At 1:02:00 · chapter starts 1:01:24
Renato Tomioka shifts the conversation to one of the most underappreciated facts in reproductive medicine: the non-linear rise in chromosomal abnormality with maternal age. [1] — Renato Tomioka "~35% aneuploidy at age 31–34: At ages 31 to 34, approximately one-third of blastocysts are aneuploid; the rate climbs to 40% by 35, 60% by …" 1:02:00 The curve is not what most people imagine — it is J-shaped, with aneuploidy rates actually higher in very young women (around 20, due to monosomy) than at 25, which represents the biological sweet spot. From 25, the rate climbs: roughly 35% at 31 to 34, 40% at 35, 60% at 38, 70% at 40, and more than 80% by 42. Almost all embryo aneuploidy (93 to 95%) originates from maternal meiotic errors, not sperm. Peter visibly reacts to these figures — he had not thought of 31 as a compromised reproductive age. Tomioka reframes IVF: it does not improve egg quality, it simply converts more ovulatory events into observable embryos. A 40-year-old who produces 8 eggs per cycle — typical for that age — will, after the successive filters of maturity, fertilization, blastocyst development, and aneuploidy screening, often be left with zero or one viable embryo to transfer. He also notes an important nuance: once you transfer a euploid embryo, implantation rates are broadly similar across ages 30 to 40, suggesting it is aneuploidy that primarily limits fertility, not other intrinsic egg qualities.
Aneuploidy by Age: The Steep, Non-Linear Cliff Every Woman Should See
At 31, roughly one-third of blastocysts are chromosomally abnormal. By 38, it's 60%. By 42, more than 80%. The curve is not linear — it accelerates. Most doctors don't show patients this table, but every woman thinking about timing her family should.
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