A new Australian National University study found that extended day care could put children at higher risk of falling behind in learning.

Literacy, maths and general academic achievement levels could suffer for pre-schoolers who spend more than 21 hours a week in day care.

One of the authors of the study, Nicholas Biddle, said in an interview with the Australian that while day care could have positive effects, too much could have an adverse impact on children’s primary school education.

“Each child is different but we tended to find a negative association from 21 hours or more. Clearly some families need such care, but we need to make sure that those who do need it have ¬access to quality care,” he said.

3,500 children aged four and five who were not attending school full-time were involved in the research. Of this number, 14% were attending day care for more than 20 hours a week.