Age & male fertility

How testosterone declines with age

Testosterone declines gradually with age, starting at around 40 years old and at a rate of approximately 1% to 2% per year.
Revised on
July 16, 2026
The risk of genetic mutations with paternal age

The risk of genetic mutations with paternal age

Healthy sperm from older and younger men appear nearly identical under a microscope.
Revised on
March 17, 2020