The child who understands what is being said, but says very little, is not likely to be suffering from developmental delay. Very slow development, however, may indicate hearing or vision problems and should be evaluated. Slower starters can often excel at football or tennis too, however. Very slow starters should be evaluated for physical or health impediments. The baby who takes a little longer has as much chance later on, however.
Babies lift their heads before they can sit up, and they sit up before they can stand.
A child develops from the trunk out to the limbs. Babies use their arms before they use the hands, and they use their hands before they use their fingers. Development moves from the simple to the complex. No matter what the child's rate of development, what is accomplished in the first year is remarkable. A person never again learns so much in so short a time.