An increase in the number of children covered by each early-childhood licence will lead to supermarket-style education, says teachers union the New Zealand Education Institute.
From July, the number of children allowed on a single licence will jump from 50 to 150 and the maximum number of children under two will be 75.
Union spokesperson Hayley Whitaker says that is too many.
But the Early Childhood Council says the change is only administrative and it will help centres that already have more than 50 children and more than one licence.
The Childcare Association says it is worried there was no consultation before the change and is unhappy that one centre could have 75 babies.