Featured Stories on BackYard Chickens
The outcome for the bird would depend in large part on the cause of the retarded growth - if it is nutritional that can often be overcome with adjusted nutrition, if it is health related the health problem would dictate the outcome as some issues are fatal and others are not.
Is one of your chicks currently having growth issues? If so, how old is the bird and how far behind others the same age is the bird? Have you tried taking steps to assure the bird gets equal access to feed/water rather than being prevented by it's bigger brooder-mates (the farther along the disparity in size/vigor gets the worse the deprivation gets so the cycle spirals further and further down.