Does my child need a speech and language therapist? How can I know?

If your child is between 12-24 months old and has these signs, your child should be referred to a speech and language therapist:
1- Does not know his or her name or says “dada, mama”.
2- Does not make any kind of gesture to communicate with others, such as pointing with fingers.
3- Does not try to imitate words he or she hears or gestures he or she sees.
If your child is between 24-36 months old, your child should be able to:
1- Say between 50-500 words.
2- Be able to understand the questions “who?” or “where?”
3- Distinguish between basic concepts “day and night?”