One in four babies is not receiving all of its core health checks in the first year of its life, according to new data.
Those children could be at risk of having conditions, including hearing and vision difficulties, go undiagnosed for years, Conectus and The Immunisation Advisory Centre at the University of Auckland said at the start of Well Child Week, which runs from today until Saturday, February 28.
More work is needed, the organisations said, to ensure infants receive all the health checks they are entitled to.
It came after data was recently released by the Ministry of Health showing one in four babies was not receiving all of its core Well Child contacts in its first year.
The Well Child Tamariki Ora service provides regular health checks for infants and also checks parents receive the support they need. Well Child Week is an opportunity for communities to find out more about the free service.
"When babies are assessed from birth, any issues that may need addressing are picked up early and can be sorted out," Dr Pat Tuohy, the Ministry of Health's chief advisor for child and youth health, said.
"Hearing and vision problems, for example, can be identified early - giving families time to seek help well before school."
However, figures from the B4 School Check showed uptake was high for that service.
In the 2013/14 year, the programme reached 91 per cent of all 4-year-olds, an increase of 11 per cent on the previous 12 months. Uptake was at 90 per cent among those living in high deprivation areas.
The figures come as, a new pilot project was launched in Waikato is aimed at addressing early enrolment and prevent children from missing out on important health services. The National Child Health Information Programme (NCHIP) aims to "ensure no child falls between the cracks of the health system".
Health providers across Waikato - including GPs, Plunket and Well Child - will be able to log on to a secure website to see whether or not a child is receiving their health milestones, such as immunisations, hearing tests and oral health check-ups.
If a health professional is unable to contact the family of a child who is due for a health check, the coordination service will launch a wider search for that child. It is hoped this will help locate vulnerable children who may otherwise drop off the radar of health services.
Meanwhile, Well Child organisers urged parents and caregivers to recognise the 'power of play', describing play as "toddlers' work".
"Play is how children learn, grow, and develop their ideas about how the world works - it's also a lot of fun," Veronica Pitt, operations manager of the New Zealand Playcentre Federation, said.
"Following the child's lead, parents can play alongside and support their child as they learn the skills that will assist them in the future - things like creativity, persistence, empathy, problem solving, and social skills.
"We believe that parents are the first and best educators of their children, and play is the best tool for learning."