Does Age Affect Male Fertility?

Middle-aged man holding a baby.

How Does Age Affect Male Fertility?

The chances of successfully getting a partner pregnant decreases with a man’s age. Both sperm quality and fertility begin to significantly decline in men during their early 40s. It also increases not only the time it takes to achieve a successful pregnancy, but the risk for miscarriage and fetal death as well.

Mental health issues are more common in children of older fathers (though it’s still rare). Children born to fathers over the age of 40 are also five times more likely to have some form of ASD (autistic spectrum disorder) compared to fathers aged 30 and under .

Additionally, there is a slightly greater risk that the child will eventually develop schizophrenia or other mental illness at some point during his or her life.

At What Age Is A Man’s Fertility Highest?

It’s not known at what age precisely that men become most fertile. However, according to the CDC (Centers for Disease Control and Prevention), the birth rate is highest for men between 25-29 years old.

Additionally, the majority of men will experience a substantial decline in fertility after reaching the age of 40. Research also shows that this decline initially starts sometime around the age of 35.

For example, one study showed that men over 35 years old had fertility rates of 25%, while those under 35 had fertility rates of greater than 50%. Other research also concluded that male fertility starts to decrease at age 35, and suggested that men are most fertile between the ages of 30-35.

Chart showing male fertility by age.
Birth rate by age per 1000 fathers. (Source: CDC)

At What Age Does Sperm Production Stop In Men?

Generally speaking, sperm production in men does not stop at any age, and men don’t stop ejaculating due to age. Even so, there is a noticeable decrease in sperm quality as men grow older. This includes parameters such as sperm count, shape (morphology), and movement (motility).

Men may notice a decline in these sperm quality values at around 35 years of age.

Fertility-Related Problems Due To A Man’s Age

The father’s age is one of the most important factors that can affect a couple’s chances of successfully conceiving, as well as the outcome of their pregnancy. The sperm health of men who are 35-40 years old and older is often adversely affected by age, and can lead to the following:

  • Decreased fertility rates – As paternal age increases, pregnancy rates decrease. By the time a man reaches the age of 40, he will typically experience a more than 50% drop in the rate of fertility.
  • Longer time to conceive – Men age 45 and up are over twelve times more likely to take more than two years to conceive, compared to men 25 and under .
  • Higher risk of miscarriage – Fathers aged 35 and older are over 25% more likely to lose their child during the 6-20 week gestation period. This risk increases to over 50% for fathers over 50.
  • Complications during birth – Pregnancies involving a man who is over the age of 45 have a greater risk for having complications during birth.
  • Increased risk of disorders in the child – Although the chances are typically low, research indicates that older men may have an increased risk of fathering children with schizophrenia, bipolar disorder, autism, Down syndrome, autism, or leukemia. Random mutations in a man’s sperm that accumulate over time are thought to potentially pass genetic changes to their children. These mutations could increase the probability of them developing a cognitive, neurological or psychological disorder.

Why Does Age Affect Male Fertility?

Male fertility is affected by age because of changes in certain sperm quality parameters (measurements). These are sperm count/concentration, sperm motility, sperm morphology and DNA fragmentation.

Decrease In Sperm Count

The sperm count refers to the number of sperm contained in the semen after ejaculation. Having a low sperm count can reduce the chances of your partner becoming pregnant.

While studies have not directly linked a reduction in sperm count with age, there has been some evidence to suggest it. One study showed a decline in sperm count by up to around 2.5% for every year of a man’s age.

Although the results are not conclusive when it comes to the effects of age on sperm count, there is more to fertility than just sperm count alone.

Reduced Sperm Motility

Sperm motility is a term that refers to the ability of sperm to move, or swim. Sperm that have low motility have a lower chance of fertilizing an egg.

Studies indicate that sperm motility may be reduced by 0.8% for every year of a man’s age. Compared to the motility of sperm of men aged 30-35, those over 55 had a 54% reduction in sperm motility.

Abnormal Sperm Morphology

Sperm morphology refers to the size, shape, and structure of the sperm. Healthy sperm cells should have a well-formed head with a cap, midpiece and tail.

Having a high percentage of sperm with abnormal morphology is actually not uncommon in men. Indeed, sperm morphology values as low as 4% can still be considered normal. However, this number tends to decrease over time.

Research suggests that sperm morphology decreases by 0.65% for every year of a man’s age.

Sperm DNA Fragmentation

DNA Fragmentation refers to damage that occurs to the sperm’s genetic material (DNA). Higher quality sperm will show a low amount of fragmentation.

Research indicates that sperm DNA fragmentation increases by 0.3% for every year of a man’s age.

How To Improve Male Fertility As You Age

Aging is an inevitable part of life. While there are ways to improve sperm quality, it is impossible to completely halt the negative effects that aging has on male fertility.

Making positive lifestyle choices is the best way for you to improve sperm health. This includes:

  • Eating a diet of healthy, nutrient-rich foods
  • Getting regular exercise
  • Not smoking
  • Reducing alcohol intake

Making these changes to your lifestyle is the most effective way to improve not only your fertility and sperm quality, but your overall health as well.

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