Parents offered advice on exercise for under-5s
For the first time government health experts are issuing advice to parents on exercise for children under five.
They say the amount of time babies and toddlers spend strapped in buggies or car seats should be cut down.
Instead, toddlers should be allowed to move around or be physically active for at least three hours a day.
The new guidance reflects growing concern over children who do not exercise enough, which can be linked to obesity and brain development.
Chief Medical Officers for England, Scotland, Wales and Northern Ireland have come together to issue the new guidance.
It is the first time they have combined to issue UK-wide advice on exercise among the under-fives.
Their recommendations include encouraging babies to move about and be active from birth, for example on activity mats or swimming.
They say that all under-fives should spend as little time as possible being restrained or sitting still except when they are sleeping.
And once a child can walk, they should be physically active and moving around for at least three hours a day.
Dame Sally Davies, Chief Medical Officer for England, said all young children should be encouraged to be active.
"For children that are not yet walking, there is considerable international evidence that letting children crawl, play or roll around on the floor is essential during early years.
"Play that allows under-fives to move about is critical and three hours a day is essential.
"I think there are parents who are not aware how important it is for their children to be physically active for a minimum of three hours.
"Other parents are very busy and may not see how important it is to get that prioritisation and balance right.
"So what I'm saying is this matters to your child now, to their development through childhood and adolescence and to their disease profile in middle age and later life."
According to the Department of Health, recent studies suggest that only about 30% of children in England between the age of two and 15 get the recommended amount of exercise.
'Huff and puff'
Most UK pre-school children currently spend between two and two-and-a-half hours a day being active.
'Active play' is described as something like using a climbing frame or riding a bike, running or chasing games, swimming or skipping - anything that makes a child 'huff and puff'.
For babies the advice is to let children crawl and roll on a mat, encouraging them to reach out and grab toys or taking them for a baby swimming lesson.
But the charity and campaign group The Children's Society says many parents need help in order to ensure their children get enough exercise.
Elaine Hindal, director of the Children's Society Campaign for Childhood, says: "Parents, particularly those from disadvantaged backgrounds, need access to good quality low-cost play facilities, childcare and support from health visitors.
"Guidance is a step in the right direction, but real practical support for parents and families is badly needed.
"We are concerned that the government's welfare reforms and spending cuts will lead to parents being denied the opportunity to provide toddlers with necessary physical exercise."
But the guidance was welcomed by Professor Terence Stephenson, president of the Royal College of Paediatrics and Child Health, who said: "The early years shape every child's future.
"Physical activity is important from an early age - if a toddler spends too much time sitting passively in front of a TV then problems will be stored up for the future.
"These guidelines offer an excellent first step and an active childhood helps to lay the foundations for an adulthood with less risk of health problems such as obesity, heart disease and diabetes."