When Time Isn’t Neutral: Paternal Age Over 50 and Fertility
Paternal age over 50 years decreases assisted reproductive technology (ART) success: A single UK center retrospective analysis. Morris G, Mavrelos D, Odia R, Viñals Gonzalez X, Cawood S, Yasmin E, Saab W, Serhal P, Seshadri S. Acta Obstet Gynecol Scand. 2021 Oct;100(10):1858-1867. doi: 10.1111/aogs.14221. Epub 2021 Aug 17. PMID: 34405396.
We live in an age where biology is often treated like a negotiable contract. Freeze this. Delay that. Optimize later. For a long time, the conversation around fertility has focused almost exclusively on women—their biological clocks, their timelines, their trade-offs. Men, culturally speaking, have been told a comforting story: You’ve got time.
But here’s the truth that changes the game: time is not neutral for men either. A large UK study published in Acta Obstetricia et Gynecologica Scandinavica delivers a clear, data-driven message—one that matters deeply for couples, clinicians, and anyone making long-term life decisions. When paternal age crosses 50, the odds shift in a very real way.
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Yes. The study reports that only 42% of men over 50 met WHO standard semen criteria, compared with ~60% of younger men.
Despite the use of techniques such as ICSI, outcomes still declined, suggesting that bypassing basic sperm parameters doesn’t fully solve the problem.
Why does this research matter?
For individuals, this research highlights something that often gets overlooked: men’s age matters too. The study found that when a male partner is over 50, the chances of achieving a live birth through IVF or ICSI are lower; even when the female partner is younger. This doesn’t mean parenthood isn’t possible, but it does mean timing and informed decisions are important. Understanding how both partners’ ages affect fertility can help you plan earlier, explore options sooner, and have more honest conversations with your care team about expectations and choices.
For professionals, this study fills a critical evidence gap. Previous research on paternal age has been inconsistent—often limited by younger male age cut-offs, donor oocyte models, or insufficient sample sizes of men over 50. This study stands out because it includes 200 men aged 51 and older, uses autologous oocytes, and applies multivariate regression to isolate paternal age from maternal age.
Among the 4,833 IVF and ICSI cycles analyzed, the overall live birth rate was 40.8%. However, this rate declined steadily with increasing paternal age and became most pronounced in men aged 51 years and older. In this group, the live birth rate fell to 29.5%, compared with 48.9% in men aged 35 years or younger.
In detail… After adjusting for maternal age, paternal age ≥51 years was associated with a 33% reduction in the odds of achieving a live birth (odds ratio 0.674, 95% confidence interval 0.482–0.943). A similar effect was observed for clinical pregnancy, with men over 50 experiencing a 36% reduction in the odds of achieving a clinical pregnancy compared with younger men (odds ratio 0.643, 95% CI 0.461–0.897). These reductions were observed across all maternal age groups, indicating that a younger female partner did not fully offset the effect of advanced paternal age.
In contrast, miscarriage rates were not independently affected by paternal age. Miscarriage occurred in 3.2% of pregnancies in men aged 51 years and older, a rate comparable to younger paternal age groups, and paternal age ≥51 was not a significant predictor of miscarriage in multivariate analysis (odds ratio 0.678, p = 0.214). Instead, miscarriage risk increased primarily with maternal age, particularly in women aged 38 years and above.
Practical Takeaways
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Not a countdown clock—but a curve. And after 50, that curve bends downward in measurable ways.
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Advanced lab techniques can bypass some barriers, but they cannot fully compensate for age-related sperm DNA damage.
