The poorest Kiwi children are now no better off than some children in the slums of India, a leading author says.

Professor Jonathan Boston, co-author of Child Poverty in New Zealand, said at the book's launch in Auckland last night that he saw worse poverty in some Kiwi families than he saw when he spent a month late last year in Delhi slums where his wife, Dr Mary Hutchinson, worked as a volunteer doctor for a Christian charity.

"The Indian Government feeds every primary school child lunch every day for 130 million children," he said.

"We saw very few seriously malnourished children in the slums of Delhi.


"India has about half of the world's poorest children, but there are children in New Zealand living in circumstances that are not that much different from those in the slums of Delhi.

"They are in houses that don't have heating, in caravans that don't have running water, and in families that simply don't have enough food of the right kind every day."

He said that even in India, poverty was relative. Most slum children went to school, health services were available and a high proportion of adults were working, albeit for low wages.

"It's on a long continuum, and in terms of that continuum some of our children overlap with the circumstances of children in developing countries in a way that I find quite shocking."

Children's Commissioner Dr Russell Wills, who appointed Dr Boston as co-chair of an expert group on child poverty two years ago, said New Zealand's living standards would drop in the future unless it invested more in the children -- mainly Maori and Pacific -- who now arrived at school at age 5 with the language of a 3-year-old.

"If we invest where it makes the biggest difference -- in preschool -- in the kind of evidence-based interventions that we know work, we can virtually guarantee that children will arrive at school at age 5 ready to learn," he said. "If we invest in those children, they will succeed."