A new study of language development of New Zealand toddlers has revealed a gap between the skills of boys and girls.
The research, part of the Growing Up in New Zealand longitudinal study, found 87 percent of two year olds are combining words into simple sentences in at least one language.
However, Professor Elaine Reese from Otago University said the study also showed the girls' vocabularies were 7 percent larger than boys', and children growing up in poorer neighbourhoods use 12 percent fewer words than those from more affluent areas.
She said vocabulary was the bedrock of reading and academic achievement so finding such pronounced gaps was a worry. And she said similar results have been found in other countries and in the United States - and is referred to as the '30 million word gap'.
"What that referred to is that in the US, children from low income households, by the time they go to school, have heard 30 million fewer words than a child from a middle class family so that is a huge gap and it portends differences in how those children do in school."
Professor Reese said by the age of two most toddlers should be combining words into short little sentences.
She said the study looked at children speaking both te reo Māori and English and fortunately, 80 percent of them were combining words in at least one language by the age of two.
The best way to help a toddler develop language skills was to have conversations with the child everyday, she said.
"One really great technique with toddlers is to follow whatever they're looking at and to say more about it and to talk about what they're interested in, not trying to change the topic to something you're interested in."