Children living in poverty are three times more likely to suffer mental health problems than others, a psychologist says.
The Child Poverty Action Group and the Psychological Society have collected international and local research on the way poverty affects children's mental wellbeing.
Among the studies was Canadian research that found poor children were more likely to be diagnosed with conduct and attention-deficit disorders and had higher levels of depression.
Clinical psychologist Kerry Gibson, an associate professor at the University of Auckland's School of Psychology, said the evidence was unequivocal that poverty could affect children's development.
"If you don't get enough nutrition the brain doesn't develop in a healthy way.
"But also the children experience a lot of anxiety, for example about not getting enough to eat, a lot of shame about having an empty lunch box and having to pretend that they have something in it."
Dr Gibson said overworked parents who could not provide support also affected children's mental state.
She said measures to prevent poverty and better mental health support were needed.