Most preschoolers are still drinking full-fat milk, despite dietary guidelines that children over two should be given the low-fat variety, according to a Massey University study.
The study involved 1330 children aged two to five, and researchers found that nine in 10 regularly drank cow's milk.
Of those, three-quarters had the full-fat version.
The Ministry of Health recommends that children over two consume two to three servings of preferably reduced-fat milk or dairy products each day.
Associate Professor Pamela von Hurst says younger children often drink a lot of milk, so the fat-reduced option not only lowers their intake of saturated fat, but also total energy.
"At the same time, fat-reduced milk has more protein and calcium than full-fat milk," she said.
"For these reasons, fat-reduced milk can be a better option for the whole family."
The researchers found that consumption of low or reduced-fat milk was influenced by socio-demographic factors.
These included age, maternal education, ethnicity and residential region.
Children were more likely to drink low-fat milk if they were older, had mothers with post-secondary education, were Pakeha or lived in the north of New Zealand.
The authors of the study, published in the NZ Medical Journal, said the geographical relationship was unclear.
One explanation could be that those participants living in the central and southern regions might have been in areas where dairy farmers were more likely to feed their child full-fat milk.
The authors said identifying the factors that influenced what type of milk children drank provided guidance for ways to improve milk consumption behaviour.