Significant speech and language delays are directly related to developmental or medical issues.
Sometimes people make assumptions about speech and language development or think that
other factors are the reason for the delays:
-Individual developmental variation: While there is variability in acquisition of speech and
language milestones, don’t assume that delays in talking are the result of normal developmental
differences between children. Research indicates that approximately 40-50% of children who
are late to talk (who have typical skills in other areas) do not catch up on their own. While some
children learn and use new words faster than others do, if your child is not saying their first
words by 15 months, or can say fewer than 50 words by 24 months, talk to your doctor.
-Having older siblings. Younger children may begin to talk slightly later than their older
brothers or sisters did. However, having one or more older siblings does not cause speech and
language delays. Studies have shown that, while older siblings often interrupt and talk for their
younger siblings, this does not seem to have a negative impact on the younger sibling’s
development.
-Being a boy. It is true that boys tend to produce their first words and sentences later than
girls. However, these differences are slight (a matter of a few months), and boys still acquire
their language milestones within the normal range of development. So if a young boy is really
lagging behind in his speech and language development, don’t assume that it’s because he’s a
boy. Significant delays are not caused by gender.
-Bilingualism. Children raised in bilingual homes may have a slight delay in beginning to
speak. However, children learning two languages will go through the same developmental
patterns in both of their languages and at roughly the same time as children learning one
language. While the vocabulary of each individual language might be smaller when counted
separately, the total vocabulary of bilingual children is comparable to monolingual children. They
also may mix both languages until they are about 3 to 4 years old, after which they usually
speak them both well. Typically developing children who grow up in bilingual homes do not have
more difficulty in learning to talk, read, and write than those who are learning one language. In
fact, learning two or more languages at a young age may boost a child's overall ability to learn.
Find links to supporting research at this post on hanen.org.