The Child Development Service, funded by the Ministry of Health, helps children with developmental delays, intellectual or sensory disabilities, syndromes, neuro-degenerative disorders and motor-skills delay.
Waikato DHB board member Mary Anne Gill said she was concerned about the delays.
Parents just wanted to know what was wrong with their children and how they could help them, she said.
The waiting time in Waikato appeared to be particularly long for children with potential autism and other behavioural issues, she said.
"If we can set children on a journey before they start school which prevents intervention from other services later on in life, eg justice or mental health, then surely we are saving money in the long run because we are actually putting things and systems in place to ensure that child has every chance of having a good start in life."
Waikato DHB board member Martin Gallagher said early detection and diagnosis of young people was crucial, and he supported working with medical professionals on the ground to improve the service.
"What's not acceptable is if kids are waiting for long periods of time to get to the Child Development Centre."
In a committee report heard on Wednesday, Waikato DHB older persons, rehabilitation and allied health director Barbara Garbutt blamed a lack of direction from the ministry regarding the roles and responsibilities for DHBs and other organisations running the service. The report also said there were long waits for the help in other parts of the country.
Ministry of Health disability support services group manager Tony Atkinson said changes were being made to the current service with a key focus on reducing wait times. The ministry was also addressing issues regarding making it accessible to everyone and more consistent around the country.
Waikato DHB was also carrying out an independent review of its own services ensuring it was delivering what it was supposed to for patients, while waiting for the outcome of the ministry review.