Is it a common practice to leave a child with a baby-sitter/nurse before the age a child may go to nursery?

Question

so that the mother can go to work?

Answer 1

Most moms would prefer an in-home baby sitter for infants under a certain age to insure that the baby is well cared for.  However, this is a luxury that's hard to pay for as well as locate.  

Our town has one daycare that takes infants at 12 weeks of age.  They have a special "baby house" that's completely separate from where the toddlers stay that has more caregivers per baby.  This is really nice for the moms with tiny babies.

Answer 2

In the USA a child goes to daycare when the mother goes back to work, most mothers take off 6-12 weeks. Some daycare won't take newborns so they have to go to babysitters.

Nursery I believe is a British term, not sure it that is  preschool or another kind of daycare.