Men also have a biological clock – they too experience a natural decline in their testosterone levels as they age. This causes a decrease in their sex drive and energy levels, and makes it difficult for them to achieve and maintain an erection. 

Men's Biological Clock

According to Dr. Harry Fisch, the author of "The Male Biological Clock", male infertility increases with age, along with a decline in testosterone levels, and decreased sperm quality .

Older men are more likely to father children with a significant genetic abnormality than younger men. This genetic abnormality arises in the babies that are born of the sperm of older men. As with women, men's biological clocks also start ticking around the age of thirty to thirty-five.

When men get older they often experience a decrease in their ability to produce quality sperm. This means it will take an older man much longer to conceive a child than a younger man.

If both partners are over the age of 35, they should consider genetic testing to make sure there are no issues with their ability to conceive.

Sperm Regeneration

Sperm cells constantly renew themselves. Nevertheless, this continual renewal of sperm cells can cause a genetic mutation.

As a man ages, there is an increase in abnormalities present in his sperm. Not only is there a decrease in the number of normal sperm produced, there is also a decrease in the quality of those sperm that are produced.

Improving Sperm with Lifestyle Factors

It is possible to slow down your biological clock by leading a healthier lifestyle.

Healthy lifestyle changes include giving up smoking and drinking, and eating a healthier more balanced diet. Also recommended is taking care of varicoceles, which are enlarged veins in the scrotum that can cause problems with sperm production in men.

Being overweight or obese lowers a man's testosterone levels and increases his risk of having infertility problems, especially if he is over 35. A man's waistline is a good indicator of his testosterone levels. The larger his waist, the lower his testosterone level.

Being underweight can also affect your sperm negatively.  If you have a BMI of less than twenty you increase your chances of having low sperm count. 

Environmental toxins such as heavy metals are also known to cause problems of male fertility — large concentrations of lead and cadmium caused by smoking decrease sperm. Mercury derived from fish plays a part as well.

Another form of pollution that affects men is environmental toxins such as heavy metals. These can cause problems of male fertility — large concentrations of lead and cadmium caused by smoking decrease sperm. Mercury derived from fish plays a part as well. 

If you are older and want to start a family, making lifestyle changes can improve your overall fertility and improve your chances of conceiving successfully.