Boys born to older women are more likely to develop heart problems later in life, warn researchers.
Delayed motherhood is already known to increase the risk of complications in pregnancy.
Now scientists have found the growing trend of putting careers ahead of starting a family could have an even bigger impact on future generations than feared.
In experiments, males born to older female rats, equivalent in age to a woman of 35, had weaker hearts and blood vessels.
The research team at the University of Alberta, Canada, said it demonstrates postponing parenthood makes offspring more prone to cardiovascular disease as adults.
Female offspring did not suffer the same effect. Principal investigator Professor Sandra Davidge said: ‘This research is important because it improves our understanding of the impact of giving birth at an older age.’
In future studies, the researchers will look into whether or not the findings published in The Journal of Physiology are true in humans. Prof Davidge said a particular focus would be the role of the placenta.
The British Fertility Society has warned that celebrities having children in their 40s are giving false hope about late motherhood as ‘miracle babies’ will often have needed IVF or donors.