'Baby on Board' stickers in car rear windows have been blamed for as many as two million - one in 20 - accidents a year, according to a survey.
The stickers – designed to encourage other motorists to drive more carefully and to help the emergency services in the case of a crash (or to boast about a driver's fertility, whichever way you care to look at it) – can obscure a motorist's vision and lead to a prang or worse.
The findings by Confused.com have led to calls for drivers to use the signs with discretion.
According to the poll of 2,000 drivers, 46 per cent of parents displayed the stickers irrespective of whether there was a child in the car at the time or not. In addition 15 per cent said they had the stickers for their novelty value, while 46 per cent regarded them as a hazard.
"Motorists need to ensure that their view is not obscured and that they have a clear view of the road around them at all times," said a Department for Transport spokesman.
There was also an appeal for drivers to generally cut the clutter in the cars for safety reasons.
"'Baby On Board' signs are useful in alerting the emergency services that a child may be involved in the event of a crash," said Julie Townsend, deputy chief executive of the charity, Brake.
"This help can become a hindrance if drivers display signs when their child isn't in the vehicle.
"Worse still is the danger that can be posed by drivers obscuring their view by cluttering up windows with lots of signs.
"Drivers' priority should always be getting there safely without putting themselves, young passengers or other road users at risk."
But the findings have been questioned by Andrew Howard, the AA's head of road safety.
"There are 150,000 injury accidents a year and about 10 times as many metal to metal crunches," he said.
"According to the Government's own figures, in car distraction is responsible for about three per cent, with vehicle blind spots for another two per cent on top of that.
"The baby on board signs are there to alert the emergency services that there is a child in the car in the event of an accident.
"Motorists should, of course, put stickers in a windscreen where it doesn't interfere with your view."
Robert Gifford, executive director of the Parliamentary Advisory Council for Transport Safety, also was cautious about the findings.
"I think we have to be very careful not to draw too many conclusions from these self-reported figures – drivers will always try to find something else to blame than their own misjudgement."
More on Parentdish: Boastful car stickers: Are you having a laugh?