The question of whether a 90-year-old man can get a woman pregnant has a straightforward biological answer: yes, it is possible. Unlike women, who experience a clear reproductive cutoff with menopause, men continue to produce sperm throughout their entire lives, meaning there is no absolute age limit for conception. However, the probability of achieving a successful pregnancy decreases significantly with advanced paternal age. Male fertility, the ability to produce viable sperm and successfully conceive a child, undergoes a gradual decline that begins around age 40, making conception rare at extreme ages.
How Male Fertility Changes with Advanced Age
The decline in a man’s reproductive capacity is driven by systemic changes in the hormonal and structural components of the reproductive system. Testosterone levels, the primary male sex hormone, begin a steady decline of approximately one percent per year starting around age 30. This reduction directly impacts spermatogenesis, the process of sperm production, and can affect libido and erectile function.
The body attempts to compensate for this decline by increasing the secretion of pituitary hormones, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). However, this mechanism is often insufficient because the testes become less responsive to stimulation. The Leydig cells within the testes, responsible for producing testosterone, decrease in number and efficiency as a man ages.
The physical structure of the testes also changes over time. Testicular volume can decrease, and the seminiferous tubules, where sperm are formed, may experience degeneration. This combination of hormonal imbalance and structural alteration weakens the environment required for the production of healthy sperm, reducing the rate and quality of sperm output.
Sperm Viability and Motility in the Elderly
The measurable output of the aging reproductive system shows distinct deteriorations in physical characteristics that directly impact fertilization success. Semen volume tends to decrease with age, and total sperm count and concentration also decrease, resulting in fewer sperm available for fertilization.
The ability of sperm to successfully reach the egg is compromised by a reduction in motility, the sperm’s capacity to swim efficiently. Sperm motility is one of the most consistently affected parameters, decreasing by an estimated 0.17 to 0.8 percent per year of age. For men over 50, progressive motility may be two-fold lower compared to men in their 40s, creating a physical barrier to conception.
Beyond movement, the morphology, or normal shape, of the sperm also deteriorates, impeding the sperm’s ability to penetrate the egg. The accumulation of oxidative stress in the aging testicular environment contributes to these physical and functional defects. These factors mean that even if sperm are present in the ejaculate of a man in his 90s, they are significantly less likely to be capable of fertilization.
Potential Health Risks Associated with Advanced Paternal Age
Conception with advanced paternal age is associated with an increased risk of certain health issues in the resulting offspring, independent of the physical challenges of achieving pregnancy. Unlike the female germline, which is static, the male germline involves continuous cell division throughout life to produce sperm. Each cell division offers an opportunity for a random error, or de novo mutation, to occur in the DNA.
Older fathers accumulate more of these new mutations in their sperm DNA, which can be passed on to the child. For example, the risk of a harmful genetic mutation in sperm increases from about one in 50 in a man in his early 30s to one in 20 for a man in his 70s. This accumulation is linked to an elevated risk for single-gene dominant disorders, such as achondroplasia, which is about eight times more likely in children of fathers over 50.
Advanced paternal age is also associated with an increased risk for complex neurodevelopmental and psychiatric disorders. These conditions include autism spectrum disorder and schizophrenia, which are linked to the accumulation of de novo mutations in the father’s germline. Furthermore, increased sperm DNA fragmentation in older men is associated with a higher rate of miscarriage and chromosomal abnormalities in the embryo.