Emergency doctors and safety campaigners are calling for a national home-visiting scheme to help prevent injuries to toddlers.
The Royal College of Emergency Medicine and the Royal Society for the Prevention of Accidents (RoSPA) say it would make a "huge difference".
They argue it would reduce pressure on A&E and save money for the NHS.
Public Health England says it is supporting health visitors in their work to prevent accidents.
Bumps and tumbles can be a lot of fun for toddlers, particularly in a safe, controlled environment.
But under-fives are particularly prone to injuries in and around the home, resulting in nearly half a million visits to emergency departments in England each year.
Recent data from Oxfordshire - highlighted by the two organisations - suggests that in about one in five attendances, there is a "threat to life or limb and/or severe pain".
Based on experience from previous injury-prevention programmes, they say a sustained £20m home-visiting scheme with professional safety advisers could reduce emergency treatment for under-fives by 30%.
They have used Department of Health cost figures to estimate this would save the health service more than £40m.
They want a universal programme, starting in England, and then rolled out across the UK. The advisers would work in partnership with health visitors offering education and advice and - where appropriate - providing equipment.
Michael Corley from RoSPA says emergency departments are under huge and growing pressure and this could be an important part of the solution.
He said: "There's a lot we can do to target those areas where there's a high incidence of accidental injury - and work alongside families to point out to them the individual hazards in homes.
"We know that burns and scalds, falls especially, asphyxiation and poisoning all represent major threats to nought to five-year-olds and yet the solution to the problem is very simple."
Eustace de Sousa, the national lead for children, young people and families at Public Health England, said it was already supporting efforts to improve safety.
"Public Health England provides leadership and guidance for health visitors to strengthen their role in helping parents prevent accidents in children under five.
"We provide advice and information to local authorities on the actions they can take to help families think about what they can do at home and in public places to keep their children safer".