The union Unite's Community Practitioners and Health Visitors Association (CPHVA) says without such a safeguard health services for young people will suffer.
The call comes amid continuing cuts to public health grants to local authorities, which since 2015 have been responsible for health visiting service provision.
At the 2015 Spending Review, the government announced a 3.9 per cent real-terms cut in public health funding over the next five years.
This has resulted in £77m of cuts in 2016/17, with a further £84m taken from public health budgets in 2017/18, on top of £200m cuts in 2015/16.
Unite said it is particularly concerned that cuts are leading to a fall in health visitor numbers, with latest NHS workforce statistics showing there were 9,410 whole-time equivalent health visitors in 2016, compared with 10,309 the year before.
The figures also show a fall in school nurse numbers, from 2,725 to 2,561 over the same period.
Unite lead professional officer Obi Amadi said: "NHS health visitor numbers have been dropping almost consistently from month to month since October 2015, when the workforce was at its largest size recorded in more than a decade.
"The government needs to secure the future of community nursing by increasing and ring-fencing money for these public health professions and the vital work that they carry out with families on a daily basis.
"The public health purse strings are now held by local councils, struggling with unrelenting cuts from Whitehall. While, in theory, public health budgets are ring-fenced, in practice, council bosses can interpret what constitutes ‘public health' in flexible ways."
Last month, the government confirmed that health visitor family checks will remain a statutory requirement.
Public Health England, the government quango responsible for public health, has made ensuring councils deliver the checks a priority this year.
The CPHVA is holding a campaign meeting in the Houses of Parliament on April 26 to finalise its list of demands members can use to lobby political candidates.
