Washington: Spending a week longer in the womb may give babies a better cognitive ability, but also slightly increase their risk of having a physical disability,
a new study has claimed.
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.
Children born at the 41st week were found to score somewhat better on tests given at third through eighth grade. 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.
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.
The children of women with low education levels - defined as not having completed high school - demonstrated the largest advantage of spending another week in the womb.
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.
Researchers drew their results from 1.5 million Florida birth records between 1994 and 2002. They linked birth certificate information to public school records from 1998 to 2013.
The findings were published in the journal JAMA Pediatrics.
