What special training do the nurses have to be able to work in the neonatal icu?

Generally. You would first need to get a degree in nursing (bsn) and become a registered nurse (rn) by qualifying through the state board. Next you need undergo specialty training in neonatal intensive care with several possible routes and certifications including master of science in nursing (msn) with a focus on neonatal nursing and neonatal nurse practioner (nnp). Requirements vary from state to state.