Most men make millions of new sperm every day, but men older than 40 have fewer healthy sperm than younger men. The amount of semen (the fluid that contains sperm) and sperm motility (ability to move towards an egg) decreases continually between 20 and 80.
Research shows that in addition to a decline in sperm count and sperm motility, the DNA that makes up older sperm cells begins to break down around age 40.
