"For families in deprivation, they are very expensive items to purchase, along with all the other items you need for babies."
General manager of governance and quality Gail Bingham said the local Plunket group was "more than willing" to keep the programme going, but had been directed by the national body to stop.
The board determined it would write to Plunket and to the Ministry of Health to share its concerns.
Tania Garrett, Plunket's business community development manager, said the organisation was moving away from selling and hiring car seats, but would continue to provide car seat education and advocacy as part of a new injury prevention strategy.
"Families are increasingly choosing to buy car seats from one of the many commercial providers rather than hire a car seat from Plunket. The decline in use has led to the service running at a loss for several years.
"As a charity, it's important we use our limited funds in the most effective way to help families keep their children safe."
Jandhe Troughton, Plunket Bay of Plenty president, said the rental and sales of Plunket car seats had already finished in Opotiki and was in the process of winding up in Whakatane, with plans to exit the service in Tauranga by November.
"Although Plunket is moving away from the rental and sale of car seats in Bay of Plenty, we've still got considerable expertise in child restraints and injury prevention, which we'll continue to provide through education and safety checks."
Papamoa mother Shantelle Mahia said it was a shame Plunket was stopping the rental service, but there were other options available to parents if they could not afford a car seat.
"I think Baby Factory does hire out car seats, and whanau can come on board and help out other whanau. We just did that, I had a spare car seat in the work car which I've let out to whanau. There's no harm in asking.
"And there are lots of mums on Facebook that are always keen to help other mums out."
A New Zealand Police spokesman said ensuring the correct restraints were worn, including for children, had always been a strong focus for police, as it was one of the simplest things people could do to ensure their safety on the road.
"Last year about 40 per cent of the people killed on our roads were not wearing seatbelts. That equates to a lot of families and loved ones who could have potentially been saved considerable loss and grief," the spokesman said.
In appropriate circumstances, police could provide opportunities for those who did not have child car seats for their children to obtain an safe car seat.
This could take the form of "compliance" - giving the person a set amount of time to buy a car seat and wiping the resulting fine if this was adhered to.
"Police would rather money was spent on making children safe than paying fines."
Tauranga and Western Bay of Plenty Travel Safe programme leader Karen Smith said the Plunket car seat technicians were a valuable resource and did a lot of work not only teaching parents how to install car seats, but in training people from other agencies how to do so.
She hoped this knowledge base would be retained.