“He’s a little late to talk because his older sister talks for him”.

This statement has been made by many parents with more than one child. But is it really the case that second and third children speak later than first-borns? And if parents do see a difference in the language development of their later-born children, should they be worried?

What the research says about birth order and early language development

Many people believe that later-born children don’t get the same amount of attention or one-to-one interactions that first-borns do, causing them to talk late.

Several studies have looked at the impact of birth order on language development. While they found some interesting differences between first and later-born children’s language development, later-born children are not delayed in their language development and first-borns do not have better language skills than their siblings. Even though mothers reported that their first-borns knew and understood more words than their later-born children, the research contradicted this.

The research did produce some interesting differences in first and later-born children’s early language skills:

• First-born children reach the 50-word milestone earlier than later-born children. But later-born children catch up quickly and there are no lasting differences in vocabulary between the two siblings.[i]
• The overall language development of second-born children was the same as their first-born siblings, but second born children were more advanced in their use of pronouns (eg. my, mine, you, your)[ii]
• While first-born children were more advanced in vocabulary and grammar, later-born children were more advanced in their conversational skills[iii]  

Why do siblings have differences in early language skills?

The differences parents may see in the early language development of their first-born and second-born children may be influenced by the different language environments that each child is exposed to (by virtue of who is in the family and the kinds of interactions they have). For example, first-born children may benefit from more one-to-one attention from their parents. However, later-born children may benefit from a greater variety of conversations, such as overheard conversations between caregivers and other siblings.

This implies that overhearing and participating in conversations with older siblings helps a younger child develop language by providing a more varied and sophisticated model of conversation.

In summary, it seems that the different language environments first and second-born children are exposed to have an impact on the early language strengths each child develops. However, the research shows that differences between first- and second-borns disappear very quickly, and that a second-born child is no more likely to have a language delay than a first-born child. 

How do you know if you should be worried?

What’s most important is not whether your second-born child speaks as early or uses as many words as your first-born child, but whether or not each child is meeting the appropriate language milestones for their age. Visit our "When You Are Concerned" page for more information, and always consult a Speech-Language Pathologist or other healthcare provider if you are concerned.