Babies that are more than two weeks overdue are twice as likely to develop attention deficit hyperactivity disorder (ADHD), recent research has found.
The longer a baby spends in the womb, the higher the chance of developing "problem behaviour", according to findings published in the Journal of Epidemiology.
"They are more than twice as likely as term born children to have clinical ADHD," the authors wrote.
Researchers studied 5145 post-term babies born between 2001 and 2005 in The Netherlands, looking at the link between time spent in the womb and behavioural and emotional problems as preschool children.
The findings are seen to be "perfectly plausible" by Professor Neena Modi, an expert in neonatal medicine at Imperial College London and the Royal College of Paediatrics.
"We know that birth after your due date is associated with a whole range of problems," she told The Guardian.
"If your baby stays in the womb for too long they are more likely to be a stillbirth, or weigh too little or become more likely to have a neurological disorder, because the longer a baby stays in the womb, the more likely the placenta is to stop functioning normal," she said.
