Shock figures show hundreds of Lancashire parents are struggling to strap their children in cars safely.
In the past three years, there were 534 incidents of mum and dads breaking child seatbelt laws, and research shows that one in five parents never use a car seat - more than any other region in the UK.
Road safety campaigners said the news is “worrying” and parents need help choosing the most suitable seat, especially with new laws coming into force in February.
Currently, under UK law, children under 12 years of age, or 135cm tall, cannot use an adult belt without additional restraints, except under exceptional circumstances.
Children weighing under 15kg (2st 4lbs) must use booster seats with backs – children over this weight are permitted to use backless booster seats.
Under new legislation, the use of booster seats with backs will be extended for use by heavier and taller children up to 125cm and up to 22kg (3st 5lb).
However, the law only applies to new products on the market. It is understood parents who already own and use backless booster seats for their child will still be permitted to use them.
Research by insurance company Confused.com shows three in five North West parents are unaware of the new laws, and of those who are aware, 86 per cent do not know what they are.
Kevin Clinton, RoSPA’s head of road safety, said: “Seat belts do not fit children properly until they are at least 135 cm tall which means they cannot protect children in the same way they protect adults. The safest way for children to travel in cars is in a child seat that is suitable for their weight and size, and is correctly fitted in the car.
“Getting the right child seat for your child can be confusing because there are so many different types, and it depends on their size and weight and whether it is suitable for your car.
“However, it is very surprising and worrying that over 20 per cent of North West parents say they never use a child car seat. This puts their children at serious risk.
“Parents need advice to help them choose the most suitable seat, especially as new standards are developed and laws changed.
“Not to use a child seat is a deliberate decision and puts the child in danger as they are at risk of being ejected from the vehicle. More needs to be done to highlight these dangers, irrespective as to the distance travelled.”
High-backed child seats are safer for children than booster cushions without a back because the high back and side provides additional head protection for the child, especially in side impacts.
During random spot checks, Lancashire Police officers have come across hundreds of cases where parents have failed to adhere to child seat laws in the past three years.
In 2013 there were 328 cases, 89 in 2014 and 117 in 2015. Each breach could mean a fine of up to £500.
A spokesman for Lancashire Police said: “It is extremely important children are adequately protected when travelling on the road, and the law makes it clear which seat they should be using for their age, weight or height, and how these seats should be secured. It is also clear on seatbelt use for all motorists, not just children.
“At Lancashire Police we take road safety extremely seriously and our roads policing team is committed to tackling those in breach of the law, which could mean a fine of up to £500.
“Anyone who isn’t sure what the law states can get more information at https://www.gov.uk/seat-belts-law or at http://www.childcarseats.org.uk/choosing-using/.”