Are There Developmental Delays in Children?

Our daughter is 18 months old. When should we be alert and consult a doctor to check for possible developmental delays?

Child development experts state that early signs of developmental delays may be detected if a child shows the following characteristics:

1. No smiling, expressions of joy, or interest in others by 6 months of age or older.
2. No vocalizations, smiling, or happy facial expressions directed toward others by 9 months of age or older.
3. No babbling by 12 months of age.
4. No reciprocal behaviors, such as pointing, showing objects, reaching out, or waving, by 12 months of age.
5. No verbalizations by 16 months of age.
6. Does not say two or more words that have meaning by 24 months.
7. No babbling or social interaction at any age.