Poor health outcomes are caused by inequality in low-income households, which fail to guarantee timely access to healthcare, adequate amounts of money, and healthy housing for families with small children.
Southey also said for Māori and Pasifika under-5s, systemic disparities, colonial effects, and racism are also causing higher rates of poverty and worse health outcomes.
By addressing these disparities, the country might be able to reduce hospitalisations for respiratory infections and dental decay in our under-5 population by up to 66 per cent, Southey maintained.
"When it comes to Sudi, Māori are nine times, and Pasifika are six times more likely to die from Sudi than non-Māori and non-Pasifika infants.
"If we are to shift the dial to significantly improve positive health and development outcomes for our children under 5, we need to prioritise children (and by age and stage) as a key stakeholder group in the new health authorities; raise incomes to liveable levels; provide access to healthy homes for families with children under 5, and address systemic bias and racism that continues to persist."
The report also revealed that preschool-aged children have a significantly higher risk of dying by homicide than older kids do and that reporting of sexual assault and related cases for children under 5 has remained "appallingly constant" over the past five years despite a notable decline of 35 per cent in assaults and neglect during the same time.
The chief executive of Whānau Āwhina Plunket, Amanda Malu, said the organisation, which interacts directly with tens of thousands of families each year, had seen first-hand the effects that poverty had on our youngest Kiwis.
"If we are truly going to support our tamariki to thrive, we need to provide systematic and concrete solutions that ensure all of our tamariki truly get the best start in life."
Children's Commissioner Judge Frances Eivers said the report was a "compelling piece of work" and "giving children the best start possible must be our priority".
She is adamant the nurturing we experience as children forms the foundation of who we become as adults.
"Under-5s are particularly vulnerable. They are not out in the wider world and they have so many milestones to hit.
"We see that some children do not get the same start. We see the same themes arise again and again: poverty, housing costs and access to health services, which are often not accessible in terms of cost, where people feel judged, or where language or culture is a barrier."
Judge Eivers called for change and for the report to be taken seriously by decision-makers.
"We can do better than this, and I believe people expect us to."
Prime Minister Jacinda Ardern spoke passionately at the beginning of her campaigns about reducing the rates of child poverty in New Zealand while her Government is in power.
A spokesman for the Prime Minister said yesterday that addressing child poverty and its health impacts is a priority for the Government.
He said all nine child poverty measures had decreased since Labour came to power and its policies had helped bring 66,500 children out of poverty.
"While average incomes have increased across all family types in the last 12 months, the largest increases have generally been for families with children, reflecting policy changes, particularly to main benefit rates.
"We know there is more to do and we will keep working to reduce all impacts of poverty, including health."
