Slightly premature or late births are a cause for concern

The study by Glasgow University of 400,000 schoolchildren found those born between 37 to 39 weeks were 16% more likely to develop problems than those born at 40.

The overall risk was still relatively low, at 5% of all children.

The team suggested their findings should inform the debate on whether and when to undergo a Caesarean. Elective Caesareans are now commonly carried out at 39 weeks.

But the Royal College of Obstetricians and Gynecologists (RCOG) said very few women opted for a surgical birth without reason, and that to delay the operation could put the health of mother and baby at risk.

It has been widely reported that babies born prematurely – at 24 weeks – are significantly more likely to suffer learning difficulties and disabilities, as well as respiratory difficulties.

This is the largest study of it’s kind to track the impact these early births may have on development later on in life, analyzing data on Special Educational Needs (SEN) – a broad spectrum which can include minor learning delays, dyspraxia and attention deficit disorder.

In total, nearly 5% of the children studied were recorded as having SEN.

The likelihood of such a diagnosis decreased the longer their mother’s pregnancy had lasted, up until 42 weeks – when it rose sharply.

Health reasons may explain why some babies are born slightly early, and this in turn could be behind later development problems. While early births are not preventable, the research suggests some elective Caesareans could be reconsidered.

Lead researcher Jill Pell said: “Early term births – between 37 and 39 weeks gestation – are becoming more common, because more mothers are electing to be delivered early for non-medical reasons – so-called birth scheduling.

“These findings have implications fir clinical practice in relation to undertake elective delivery and the timing of elective deliveries.”

But Professor James Walker, a consultant and spokesperson from the RCOG said very few Caesareans were now carried out before 39 weeks and the vast majority of elective operations were for good medical reasons.

“The findings of this study do seem credible, but the risk they highlight has to be balanced against the risk of waiting for a mother to reach term. If she then goes into labour at night, or ends up having an emergency Caesarean, these present much greater risks.

“But we do all have to be aware of the consequences of medical intervention, as well as the consequences of not intervening, and make decisions accordingly. This study adds to the body of what we know.”

Cathy Warwick, general secretary of the Royal College of Midwives, said: “This new research highlights another reason for women and professionals to think carefully about the necessity for each elective caesarean section.

“There is a real need to encourage more normal births and midwives are doing this. Midwives need to have the time to spend with women to discuss all the birth options available to them, and to offer them help and advice. There are many examples of this happening across the country, and I would like to see many more.”

Latest figures have shown that a quarter of all births in the UK are carried out by Caesarean. Around 15% of these are emergency operations, and 10% are planned.