An annual survey by the Institute of Health Visiting (IHV) of 1,400 health visitors found that since family health services were transferred from the NHS to local authorities in October 2015 caseloads have increased markedly due to staff cutbacks.
According to NHS figures published in April the number of health visitors has fallen by 10 per cent over the last two years, from 10,309 in October 2015 to 9,259 in January 2017.
The IHV said this is leaving health visitors unable to offer a universal service and build close bonds with families in need of help. It said more than one in three (35 per cent) said they feel so stretched that there may be a tragedy at some point, up on 25 per cent when the same question was asked in 2015.
One in five (21 per cent) said they are now working with caseloads of more than 500 children, up on the one in eight (12 per cent) who had this number of cases two years ago.
The IHV recommends that health visitors should have no more than 250 cases at any one time in order to be able to deliver comprehensive health support.
Meanwhile, 42 per cent of health visitors said they are only able to offer continuity of care to vulnerable children and those already subject to child protection processes. This is considerably higher than the 26 per cent who reported this in the 2015 survey.
In February the government renewed legal requirements for councils to deliver five health checks to children before they are two-and-a-half years old.
But just 29 per cent said they are able to provide universal antenatal visits, nine out of 10 are able to carry out new birth visits to all families and only 76 per cent are able to offer a six-to-eight week assessment to all families.
Two thirds (67 per cent) said they are able offer a universal nine to 12 month review and a similar proportion (66 per cent) said they could offer a two to two-and-a-half year review to all families.
"We are being told that many families see a health visitor only until their child is eight weeks old, with less skilled staff carrying out all their later developmental reviews," IHV executive director Cheryll Adams said.
"Health visitors' time is being targeted to picking up work once done by social workers in some areas of the country, meaning that these health visitors are not able to deliver their primary preventative role - the only professionals previously able to offer this as a universal service.
"Without a universal preventative service many children and families in need will be missed until their problems become serious, which goes completely against the role and responsibilities of a trained health visitor and where they can have their greatest impact.
"Our worry is that the number of children needing care proceedings will increase, even more children will need mental health services, postnatal depression will go undiagnosed, there will be greater demand on GPs and hospital services and more children will enter school less well prepared in terms of their social, emotional and communication skills. Cutting the public health workforce is a false economy."
The 2015 Spending Review featured a 3.9 per cent real-terms cut in public health funding until 2020, with £84m taken from public health budgets in 2017/18, on top of £277m in cuts over the previous two years.