late talking

I have twin boys and they are 31/2 years old now.They were 35 weekers and had low birth weight.They are stil not talking very much.They can repeat and talk almost all words we say ,however,they have difficulty forming sentences.They talk only simple sentences (2-3 words)not big ones.All other develepoments seems good.They can say ,write and read letters A-Z,and numbers 1-10.Only concern is speech.Is this a delay in developement ?How can we overcome this?

[Jessica L Thomason Sassi, Ph.D., BCBA-D]

There is a lot of variability in typical development, including development of speech.  The best way for you to determine whether your children's speech is normal, however, is to have a professional do an in-person evaluation.  I would raise your concerns with their pediatrician, and get her/his opinion; if there is any doubt as to whether their speech development might be delayed, your pediatrician can help recommend a speech pathologist who can conduct a more formal evaluation.

Best of luck to you.