Children in daycare centres will be sent home early on Thursday, as some of the sector's 80,000 mostly female staff strike to narrow the large pay gap between men and women.

Several childcare centres in Melbourne's north and south-east will be forced to shut soon after 3pm, and staff will suspend normal activities at a centre in western Sydney, in a dramatic escalation of the early childhood workforce's battle for better wages.

The unprecedented strikes are set to disrupt the daycare arrangements of up to 500 children, the childcare union said.

Educators in the early childhood sector are paid as little as $20 an hour – slightly above the national minimum wage and well below average incomes of primary school teachers.