The study, which appeared in the journal Pediatrics, followed on a 2007 study by the same researchers that found babies and their parents benefited when the infants were taught to settle themselves to sleep with behavioral techniques.

London - The definition of premature birth should be raised to more than 37 weeks, experts claimed.

Even babies considered full term – between 37 and 41 weeks – could benefit from an extra fortnight in the womb, according to the study.

The additional time results in more brain development and slightly better scores in school mathematics and reading tests.

The research also raised serious questions about the growing number of Caesarean deliveries, which are sometimes scheduled for the convenience of mothers and even doctors. Under the current definition, a pre-term baby is one born at less than 37 weeks. Organ systems generally mature in the three weeks before this point and the foetus reaches adequate maturity by the end of this period.

Children arriving without 37 weeks in the womb are known to face increased chances of health and developmental problems.

According to the joint study by Columbia University Medical Centre and the New York Presbyterian Hospital, children born at 37 or 38 weeks did worse in academic tests than those born just a week or two later.

The results of the tests show women should ‘at least proceed with caution before electing to have an earlier term birth’, said Kimberly Noble, an assistant paediatrics professor at Columbia and lead author of the study.

The researchers compared birth records and test scores for 128,000 eight year olds born in New York City in the late 1980s and early 1990s. All of them had been born between the normal 37 and 41 weeks of gestation. Compared with 41-weekers, children born at 37 weeks faced a 33 percent increased chance of having severe reading difficulties and a 19 percent greater chance of having moderate problems in maths.

Judy Aschner, a paediatrics professor at America’s Vanderbilt University Medical Centre, said: “I don’t want to panic mums whose babies come at 37 weeks, but those elective early deliveries really need to stop.”

Children born at 38 weeks fared slightly better than those born at 37 weeks. - Daily Mail