I have always hated baby on board signs in cars. They suggest either that parents think you need to know they have a baby so you make a special effort not to crash into them (because it's ok to maim or kill the childfree in a car accident) or to warn you that they are going to drive badly due to being distracted.
Now I understand. It means 'expect exceptionally early braking when approaching stationary traffic or red traffic lights; I will do everything in my power to keep this car moving, however slowly, as otherwise my baby will wake up and cry all the way home'.
I still don't plan on having one.
