Children from poorer backgrounds are twice as likely to die before the age of 15 as those from affluent homes, a study revealed today.
The study by the Public Health Alliance shows factors linked to a person's economic background can put their lives at greater risk.
Children in low-income homes are more likely to be born small with low birth rates, leaving them with poorer health in later life and reduced life expectancy.
The rate of low birth weights was higher in Belfast than Dublin, but both lagged behind Scandinavian countries.
Dr Thomas Quigley, co-chair of the alliance, said the study - entitled Health Inequalities on the Island of Ireland: The Facts, the Causes, the Remedies- found poor health experiences in childhood, even before birth, were leaving lifelong scars.
It found people who are poor and socially excluded more likely to die at a younger age and experience a higher rate of ill health.
"Given the evidence of the impact of inequality on the health of the population it is clear that in both Northern Ireland and the Republic of Ireland any attempt to improve health and address inequalities in health must be rooted in social justice, resulting in a fairer distribution of wealth, as well as provision of appropriate, accessible services provided on the basis of need and not ability to pay," Dr Quigley said.
He said the alliance was calling for an end to child poverty and an equitable tax and welfare system to reduce the income gap. Another move being pushed by the group is the provision of a universal health service, providing care on the basis of need rather than ability to pay.
The study, compiled from a range of reports, states: "In the Republic, the health system is fundamentally unequal, allowing those who can afford private care to get more rapid access to a better service."
The rates of mental ill-health and suicide were detected as significantly higher in economically deprived areas, while those in lower socio-economic groups have a higher incidence of cancer and poorer survival rates compared with more affluent sectors.
The Public Health Alliance found Irish men have the lowest life expectancy of all the European Union States.
Men from the lowest socio-economic groups in Northern Ireland live an average of six-years less than those from wealthier backgrounds. Death rates among people in the lowest occupational class was up to 200 per cent higher than the rate for the highest.
Among those in the lower work classes, the death rate for circulatory diseases was 120 per cent higher, 100 per cent higher for cancers, 200 per cent higher for respiratory disease and over 150 per cent higher for injury or poison-related deaths.
In Northern Ireland, the death rate from murder or assault was 225 per cent higher in lower socio-economic groups than the highest.
Women in the Republic have almost twice the rate of death from heart disease as the European Union average.