After what age does male fertility begin to decrease?

50 years old - maybe: Unlike the inevitable age related decline that happens to all women, most men will continue to make sperm their entire life. There are studies suggesting that a man’s sperm count, and possible more importantly the quality (normalcy) of sperm, begins to decline around 50 years of age. A simple semen analysis can check the sperm count.

Probably does not: Male sperm quality as defined as fertilization and embryo quality at ivf seem unchanged in several studies. Other studies suggest that fertility may decline as early as 35-39. I believe much of the confusion arises over limited research and different definitions of male fertility. It would seem that while sperm counts decrease the quality does not until late age. Consult you doc. Best wishes.