A man's age and his sperm quality have a significant impact on a baby's development and the likelihood of conditions such as autism and Down syndrome, a university study has found.
The University of Otago says its analysis of research contained in 90 studies from around the world highlights how the risks associated with a man's age and fertility have long been overlooked.
The study by Otago's departments of zoology and anatomy of data taken from 94,000 patients from more than 30 countries found there are consistent age-related declines in semen volume and performance.
There are also age-related increases in malformed sperm or sperm with damaged DNA.
Semen quality is regarded as a proxy for how fertile a male is, and the study's lead author Sheri Johnson says the effects of declining semen and increasing age have largely been ignored due to inconsistencies in the literature.
"Our work now suggests that male age affects a variety of traits," said Dr Johnson.
"It is well recognised that reduced sperm performance can affect pregnancy success, but it is less well known that the quality of the sperm, particularly DNA quality, could affect the development and health of offspring."
The findings suggest further awareness is needed about how older males contribute to an increased risk of obstetric complications, miscarriage, and disorders such as autism, Down syndrome, epilepsy, and schizophrenia.
The study's authors say clinicians and the general public need to be aware of the risks associated with male age and fertility.
More accurate and consistent predictors of a man's fertility should be tested, not just commonly clinically measured traits such as semen volume, sperm concentration and total sperm count.
The study was published in the international journal Ageing Research Reviews.
source: newshub archive