ACEs include experiences of parental separation or divorce, depression in a parent and incarceration of a parent.

International studies have consistently found a group of up to 10 specific childhood experiences associated with poor outcomes later in life.

The AUT researchers found that a child’s performance in cognitive tests at four-and-a-half years of age declined in direct correlation with the number of ACEs they had experienced.

The researchers also found that more than half of New Zealand children will have an adverse childhood experience before they are four-and-a-half years old, which is on a par with findings from other international research on ACEs.

The quality of the mother-partner relationship and parental health and wellness were identified as protective factors that may allow some children to experience no ACEs, despite being at heightened risk of experiencing multiple ACEs.

The quality of the mother-partner relationship included having co-parenting support, the strength of the partnership and warmth in the relationship.

"To arrive at their findings, the researchers used data gathered from 5562 of the families in the Growing Up in New Zealand study," Rob Hodgson, General Manager Insights MSD, said.

"Growing Up in New Zealand is a contemporary longitudinal study looking at child development in New Zealand.

"The children participating in the study are turning ten years old and are broadly generalisable to the children born in New Zealand in 2009 and 2010."

"The value of the Growing Up in New Zealand study is realised through research providing insights that informs the design of policies and services that better support the diversity of families and children in New Zealand today."

Download the research reports: Protective factors of children and families at highest risk of adverse childhood experiences and Adverse childhood experiences and school readiness outcomes here.