A new study has shown that becoming a father after the age of 45 increases the likelihood that the resulting child will die before reaching adulthood. The researchers, based at the University of Aarhus in Denmark, who published their findings in the European Journal of Epidemiology, say that the reason for this is the decline in the quality of sperm as men age.
The research shows that children born from older fathers are more likely to suffer from a number of birth defects and conditions such as autism, schizophrenia or epilepsy. The majority of deaths were found to be caused by congenital defects that increased the risk of infant mortality, such as heart problems.
Children born to men aged 45 and above were found to be up to 88 per cent more likely to die before adulthood than those born to men aged between 25 and 29, the researchers found. The researchers looked at 100,000 children born between 1980 and 1996 using data taken from the Danish Fertility Database, and found that 831 of these had died before reaching the age of 13 - 601 of these died in their first year. Similar results were found for men who fathered children while still in their teens, but could perhaps be explained by their mothers also being young and often therefore disadvantaged, say the researchers.
Jin Liang Zhu, from the Danish Epidemiology Science Centre, and lead researcher in the study, said that 'the risks of older fatherhood can be very profound, and it is not something that people are always aware of'. People tend to be far more aware of the risks associated with older mothers, such as the increased prevalence of Down Syndrome, although it has also previously been shown that this may be affected by the father's age as well.
Speaking to the Melbourne Herald Sun, Professor Les Sheffield, a clinical geneticist from Melbourne's Murdoch Childrens Research Institute, explained that genetic errors in sperm increase by half a per cent when a man reaches 40, by 2 per cent when he is 50, by 5 per cent when he is 60 and by 20 per cent by the time he is 80. He added that on the basis of this, 'men around 40 ought to be thinking about the increased risk to their children, the same as women do'.
Dr Kirsty Horsey is Contributing Editor at BioNews. She is coeditor of Human Fertilisation and Embryology: Reproducing Regulation (buy this book from Amazon UK) and coauthor of Tort Law (buy this book from Amazon UK) and Skills For Law Students (buy this book from Amazon UK).