Men begin producing sperm when they reach sexual maturity and keep on producing sperm for the rest of their lives.
The production of gametes (the reproductive cells that fuse during fertilisation) is different for males and females (and for different species). In human females, all of the ova (eggs) that are released during their reproductive period (between puberty and menopause) develop before birth. The number of ova decreases with age as they are ovulated (released for fertilisation) or they degenerate and are reabsorbed. Once the supply of ova is exhausted, females become infertile.
In human males, sperm are produced continually, so they never run out and males remain fertile throughout their adult lives. Although there is no end to the production of sperm over a male’s life, it can change.
In human males, there is a small decrease in sperm count with increasing age. Other common measures of semen quality (semen volume, sperm shape and movement) also decreased with age, and DNA damage increased. The cause of these changes with age is not known but age-related degeneration of the testes (testicles), or the build-up of damage from environmental exposures or poor health, are both likely.
Partners of men aged 45 years or older take longer to fall pregnant and have a higher risk of miscarriage. And, although still rare, autism and other developmental conditions are slightly more common in children with older fathers. The risk of your child having a genetic or chromosomal problem is also increased.
Continual sperm production allows men to father children well into their old age, like Les Colley, an Australian man who holds the Guinness World Record for the oldest father of a newborn, at 92 years and 10 months.
Tim Moss
Healthy Male Health Content Manager
Associate Professor Tim Moss has PhD in physiology and more than 20 years’ experience as a biomedical research scientist. Tim stepped away from his successful academic career at the end of 2019, to apply his skills in turning complicated scientific and medical knowledge into information that all people can use to improve their health and wellbeing. Tim has written for crikey.com and Scientific American’s Observations blog, which is far more interesting than his authorship of over 150 academic publications. He has studied science communication at the Alan Alda Centre for Communicating Science in New York, and at the Department of Biological Engineering Communication Lab at MIT in Boston.
