The report, submitted to the House of Commons Health Select Committee, highlighted that health visitor numbers are at a 13 year low.
There is also a failure to train enough school nurses to tackle problems such as childhood obesity and mental health.
Unite said the role of the health visitor should be protected by law, a requirement that was lifted in 2001.
This would mean the role would be carried out only by those trained to that standard – because at present less qualified staff can undertake health visiting duties.
The report said: ‘To invest in health visiting and hence early intervention could produce massive savings to other areas of government expenditure related to inequalities in the longer term.’
The committee is currently running an investigation entitled ‘The Contribution of the NHS in Reducing Health Inequalities.’