She warned that the proportion of children arriving in primary school reception classes unsure which hand to use to catch a ball or hold a pen has trebled in the past decade.

Dr Madeleine Portwood said up to 30 per cent of children are now unable to choose which is their dominant hand, up from 10 per cent in 1998.

She claimed the trend has been fuelled by excessive parental fears, driven by cot death, which has led to many babies missing out on the crucial crawling stage of development that teaches co-ordination.

Some parents have interpreted advice that children should sleep on their backs to mean babies should never be allowed on their fronts, even when awake and on the floor, she added.

Dr Portwood, who works with Durham County Council, said: ‘Crawling is an essential part of learning coordination.

‘Children move their right hand and left leg, then left hand and right leg, and when they are able to separate out these movements it helps their brains learn other aspects of coordination.

‘But more children are not going through the crawling stage. They shuffle along on their bottoms and find a chair, table or curtains and use their arms to pull up to a
standing position.’

Presenting her findings at an independent schools conference last week, she added: ‘The most important thing parents can do is ensure that when babies are being observed during the day they are given the chance to be on their front, simple things that make such a huge difference in the future.’

 ‘Going through the crawling stage is fundamental to developing other skills. And it is important if you start formal education at four and a half and you are expected to hold an implement to write, that you know which hand to hold it in.’

She said children are often wrongly identified as having developmental problems if they cannot draw or write, when in reality their difficulties may stem from having not yet established which is their dominant hand.

Previous research by Dr Portwood also found 57 per cent of three-year olds are so uncoordinated they are unable to carry out basic tasks expected at their age.

Many are unable to run in a straight line or avoid bumping into obstacles because they are used to sitting in front of a TV or being taken everywhere in a pushchair or car.

Source: DailyMail