Researchers found that babies born at late term - 41 weeks' gestation - are slightly more likely to be classified as gifted and have higher standardised test scores than babies born at full term, or at 40 weeks' gestation.
However, babies born at 41 weeks also showed a slightly higher chance of having a physical disability than babies born at 40 weeks, researchers said.
"What our findings suggest is that while 40 weeks remains the safest time for most babies to be delivered, in uncomplicated pregnancies, going another week seems to have beneficial effects on later performance in school," said Jeffrey Roth from University of Florida in the US.
Late-term infants were 2.8 per cent more likely to be classified as gifted and 3.1 per cent less likely to have poor cognitive outcomes compared with full-term infants, researchers said.
More From This Section
Late-term infants were also 2.1 per cent more likely to be classified as having a physical disability that requires special classroom accommodation, they said.
These physical disabilities most commonly include speech pathologies as well as sensory disorders and orthopedic conditions, and can include children being homebound or hospitalised.
"While late-term gestation is associated with somewhat higher rates for physical problems, it is also associated with better cognitive outcomes," said David Figlio from Northwestern University in the US.
Compared with children born full term, children born to low-education mothers at 41 weeks are 7.6 per cent more likely to be gifted and 4.2 per cent less likely to have poor cognitive outcomes, researchers said.
The differences in physical disability rates - 5.1 per cent higher than children born at 40 weeks - are also larger for the low-education group, they said.
These children may have benefited from the extra week of uninterrupted brain maturation, said Roth.
The findings were published in the journal JAMA Pediatrics.