Sperm DNA quality declines with age

Sperm contains a genetic "biological clock" that makes it more difficult for older men to have healthy children, new research has shown.

Scientists already knew that reproductive ability declined with age as sperm became less plentiful and active.

The new US study found that the genetic quality of sperm also worsened as a man aged.

An examination of sperm DNA from 97 volunteers aged 22 to 80 showed that it became steadily more fragmented as age increased. The first changes were seen in men early in their reproductive years.

DNA fragmentation is associated with greater infertility and a reduced chance of conceiving.

The sperm of older men is also more likely to carry the genetic mutation which causes achondroplasia, or dwarfism.

"This study shows that men who wait until they're older to have children are not only risking difficulties conceiving, they could also be increasing the risk of having children with genetic problems," said Dr Andrew Wyrobek, from the Lawrence Livermore National Laboratory in Livermore, California, who led the research.

The findings were published yesterday in the online edition of the journal Proceedings of the National Academy of Sciences.

The study included at least 15 men from each age decade spanning 20 to 60 years, and 25 men aged 60 to 80.

- NZPA