article_snippet.sent: Whereas the menopause marks the end of reproduction, men are able to produce sperm throughout men lives.
article_snippet.sent: Men are able to produce sperm throughout Men lives.
article_snippet.sent: In order to produce new sperm, so-called sperm 'precursor' cells have to divide.
article_snippet.sent: so-called sperm 'precursor' cells do this every 16 days, which means by the time a man reaches 70, so-called sperm 'precursor' cells will have divided around 1,500 times.
article_snippet.sent: Another explanation is that, after the age of 60, a high percentage of sperm is affected by so-called DNA fragmentation.
article_snippet.sent: Normally, the genetic material in a sperm cell is wound up like a tight ball of yarn to prevent the strands of DNA breaking.
article_snippet.sent: When the genetic material in a sperm cell is not safely packaged, the strands of DNA breaking are vulnerable to breakage, or DNA fragmentation, which means the fertilised egg may not be able to develop normally and, in some cases, become unviable.
article_snippet.sent: With age, a man's testosterone levels also drop, with one in five men over 60 having low levels, leading to poor semen quality, which can affect conception rates.
article_snippet.sent: Dr Simon Fishel, chief executive of CARE Fertility, says: 'Even though men keep producing sperm, the decline in sperm DNA with age is now uncontroversial, with potentially devastating effects on the offspring of older men. '
article_snippet.sent: One study the researchers looked at, which set out to find a cut-off age for men, found that semen quality declined continuously with age, with no point at which risk suddenly increased.