"It has been absolutely essential for families who can't afford to buy a car seat, but want to keep their child safe.
"The loss of any service which assists our families is a disaster - and I wish to see this service continue."
Wairarapa Montessori assistant head teacher Donna Harper said the closure would impact their single-parent families.
"I've known mums who have gone without a car seat and have just taken their kids to kindy in the pushchair," Ms Harper said.
"Which is fine in summer, but not so much when it's raining and windy - unless you've got one of those expensive, fancy prams with a storm cover. A car seat is a life-saving device - it shouldn't be a money-spinner to save a child's life."
Masterton Shuttles owner Te Paea Rangi, who does Ministry of Education-funded runs, was shocked the service was ending.
Because she has to supply restraints to fit children of various sizes, Mrs Rangi understands car seats can be costly.
"You're upgrading all the time. Depending on how fast the child grows, parents can go through two or three seats."
Hayley Inder, who runs a charity donating baby products, has used the Plunket service and found it "hugely helpful".
Without it, she was concerned families would be forced to consider second-hand restraints. "Car seats do have a shelf life, so they could end up with something that's past its use-by date," Miss Inder said. "With sites like Trade Me, you're going on someone's word that what they're selling is good quality - but the seat could have been in an accident, and not as safe."
Wairarapa Advocate Services manager Trevor Mackiewicz said having to purchase "the most recent brand of car seat to comply with safety standards" would be "a strain" for beneficiaries.
He often helps families apply for Work and Income assistance but funds for car seats are usually recoverable grants, so the family is left in debt.
Wairarapa Parents Centre president Liz Mason said the lack of specialised baby retailers in Wairarapa was problematic.
"The nearest are in Palmerston North and Lower Hutt, so it's not that convenient. Plunket's is a well-used service, and it will be missed."
Plunket chief operating officer Andrea McLeod said the service had been "making a loss for several years".
Plunket car seat sites had dropped from 283 in the 1980s to 72 - with many closing or reducing hours.
Spokeswoman Jen Riches said Plunket would run specific educational programmes on child restraints, which will differ in each region.
Wairarapa families would still be able to hire and buy carseats from Plunket for some months because "nothing will change overnight."
