The fact that overdue children, born after the 42nd week of pregnancy, are ill more often than other children during the first few months is already known. This has been linked to their greater size at birth, which can lead to complications.
In the new study, scientists have followed children who were born late through their childhood and researched how they developed in their pre-school years.
354 overdue children children who were born at Huddinge hospital in 1991 were assessed and compared with a control group. The results revealed that 13% of the overdue children experienced neurological difficulties, with late motor and mental development.
Among children born after a normal gestation period the figure was just 5.5%.
Paediatric neurologist Katarina Lindström, who led the research, offered no explanation but said she doubted that the number of extra weeks of pregnancy were significant.
Instead, she said she believes that there could be underlying problems which also cause the lateness, such as a genetic damage or something which happened earlier in the pregnancy.
The research was published in the scientific journal Acta Pediatrica.