Obstetricians deliver babies, not nurses. Nurses care for newborns. Very often, healthy newborns are cared for by their mothers. NICU nurses specialize in the care of babies who are born with special needs and/or concerns. Nursing in the NICU is a specialty area.
"Nursery Nurses" are called Neonatal Nurses. In addition to delivery/feeding, they perform the first checks of the babies senses and reflexes such as vision, hearing and grasping (moro reflex).
You need to be a qualified midwife or nurse to assist in the delivery suite but nursery nurses are employed in Maternity to help new Mums with feeding, changing etc.
