There is a clear north-south divide in the number of times a child is seen by a health visitor, a parenting group has said.
A study of health trusts in England showed marked variations between the number of health visitors across the country, particularly between London and the north, the Family and Parenting Institute (FPI) said.
County Durham Primary Care Trust (PCT) had the best figure, with one health visitor for every 165 children under five, and Lambeth PCT had the worst, with one visitor for every 894 children, according to the survey.
The study also showed that eight of the 10 PCTS with the lowest number of health visitors were in London.
The FPI said the research shows a "clear north-south divide in the health visiting service".
Chief executive, Mary MacLeod, said that the "postcode lottery" is unacceptable and is calling for a universal health visitor service and better training.
She added: "The value of health visitors is unquestionable. Parents tell us they are a lifeline.
"Health visitors respond to parents' worries and concerns, and their unique relationship and position of visiting families in their home means that they can detect problems that parents may not talk about - such as postnatal depression, domestic violence or child abuse."
"The 'postcode lottery' is a national disgrace. Please learn from Northern Ireland, and implement our standards nationwide" - Elizabeth Kennedy, Groomsport
"Health visitors, midwives and community nurses were a pride to have as community workers and benefited the service, providing support. The whole community nursing service has been dessimated and the devotion and commitment of those who worked within it lost. We need to bring this back. Working in community health and health-related professions should be a devotion and not just seen as a job for gain." - V Henry