The children of older fathers perform less well in a range of cognitive tests during infancy and early childhood compared to the offspring of younger fathers, the results of a new study indicate.
In contrast, the children of older mothers achieve higher scores in the same tests.
According to Australian researchers, the age at which men and women are having children is increasing in the developed world. However while the effect of increasing maternal age on reduced fertility is widely discussed, the consequences of increased paternal age are not as well known.
Recent studies have demonstrated a link between older fathers and specific health problems in their offspring, including birth deformities and schizophrenia.
As part of this latest study, the researchers from the University of Queensland looked at the link between a father’s age and their child’s general cognitive ability. They looked at over 33,000 children who were assessed at the ages of eight months, four years and seven years. The cognitive tests used were designed to measure the ability to think and reason. They included concentration, learning, memory, speaking and reading skills.
The study found that the older a child’s father was, the more likely the child was to have lower scores on the various tests, with the exception of one measure that looked at physical coordination.
In contrast, the older the mother, the higher the scores of the child in the cognitive tests.
Previous researchers have suggested that the children of older mothers may perform better because they experience a more nurturing home environment. If this is the case, this study indicates that children of older fathers do not necessarily experience the same benefit.
The Queensland team offered a number of reasons to explain the results, including genetic and social reasons. They said that unlike a woman's eggs, which are formed when she herself is in the womb, a man's sperm accumulates over his lifetime. Previous studies have suggested that this can lead to an increased incidence of mutations in sperm at an older age.
The researchers concluded that given the trend towards older maternal and paternal ages in the developing world, policy makers may want to consider promoting an awareness of the risks to children that this study associates with delayed fatherhood.
Details of these findings are published in the journal, PloS Medicine.
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