
Wondering whether your 18 to 30-month-old child is a 
late bloomer or may have a language problem? There are some factors to look out for that can help a parent differentiate between the two. Do they understand language? Can they get their point across using gestures and other non-verbal communication? Are they rapidly progressing with language between 24-30 months of age? And lastly, if they seem to be delayed, are they still making some progress? If you've answered "no" to one or more of these questions, you may want to consider an evaluation with a speech-language pathologist.
Here is an excerpt 
from an ASHA article on the topic:
"Although the stages that children  pass through in the development of speech and language are very  consistent, the exact age when they hit these milestones varies a  lot. Factors such as the child's inborn ability to learn  language, other skills the child is learning, the amount and kind  of language the child hears, and how people respond to  communication attempts can slow down or accelerate the speed of  speech and language development. This makes it difficult to say  with certainty where any young child's speech and language  development will be in 3 months, or 1 year.
There are, however, certain factors that may increase the risk  that a late-talking child in the 18- to 30-month-old age range,  and with normal intelligence, will have continuing language  problems. These factors include:   
* Receptive language:    Understanding language generally precedes expression and use.    Some studies that have followed-up late-talking children in    this age range have found, after a year, that age-appropriate    receptive language discriminated late bloomers from children    who had true language delays. Other researchers doing follow-up    studies included only children whose receptive language was    within normal limits because they believed that delay in this    area was likely to produce worse outcomes.    
* Use of gestures:    One study has found that the number of gestures used by    late-talking children with comparably low expressive language    can indicate later language abilities. Children with a greater    number of gestures used for different communication purposes    are more likely to catch up with peers. Such a result is    supported by findings that some older children who are taught    non-verbal communication systems show a spontaneous increase in    oral communication.
   
* Age of diagnosis:    More than one study has indicated that the older the child at    time of diagnosis, the less positive the outcome. Obviously,    older children in a study have had a longer time to bloom than    younger children but have not done so, indicating that the    language delay may be more serious. Also, if a child is only    developing slowly during an age range when other children are    rapidly progressing (e.g. 24-30 months) that child will be    falling farther behind. 
   
* Progress in language development:    Although a child may be slow in language development, he or she    should still be doing new things with language at least every    month. New words may be added. The same words may be used for    different purposes. For example, "bottle" may one day    mean "That is my bottle," the next, "I want my    bottle," and the next week, "Where is my bottle? I    don't see it." Words may be combined into longer    utterances ("want bottle" "no bottle"), or    such longer utterances may occur more often.
   
It should be re-emphasized that negative aspects of these  factors increase the risk of a true language problem but do not  mandate its presence. For example, one research group found that  one of their 25- or 26-month-old children with the worst  receptive language had the best expressive language outcome 10  months later. On the other hand, children on the positive side of  these factors may turn out to show less progress than predicted.  The research group found that the child with the poorest outcome  had the best receptive language and the largest vocabulary at the  beginning of the study.
   
One study has found that the number of gestures used by  late-talking children with comparably low expressive language can  indicate later language abilities."
So what should you do if you are concerned about your child's speech and language development?
Come see one of our speech-language pathologists, and we will answer any questions you have about your child's language development. Research has shown that the time between birth and 36 months is an extremely critical period of development, so our work in 
early intervention allows us to both identify and treat very young children in an effort to minimize any potential speech and language developmental issues.
Helpful Links:
ASHA article
Developmental Speech & Language Milestones, Birth - 5 Years of Age   
Warning signs for communication disorder in young children