Is the direct Coombs test done at birth testing the baby or the mother? Whose Coombs is being tested?

Baby's Red cells and. mother's antibodies. The Direct Coombs test in a newborn is done to look for maternal antibodies that may have coated the baby's red cells. So, in a way both are being tested, but it is mainly to test for maternal antibody induced hemolytic anemia in the baby.