It’s not just older women who have a higher relative risk of rare genetic disorders in their offspring.
Older fathers, from 40 onwards, also have an increased risk of passing on genetic abnormalities.
“That probably indicates that there is some DNA degradation over time,” says Rob McLachlan, principle research fellow at the Hudson Institute in Melbourne, consultant andrologist at the Monash IVF Group and director of Andrology Australia.
Complex disorders, such as autism spectrum disorder and schizophrenia, also appear to be higher in the offspring of older fathers.
“Now, that said, these are not common,” says Dr McLachlan. While the relative risk is high, the absolute risk remains low.
Also, the influence of older fathers on offspring is nothing like the severity of the impact of female genetic abnormalities.
“I think the important thing for couples to realise is that fertility is best when you are younger.”