Going to see a perinatologist how different will it be?

my midwife has sent me to a perinatologist due to a chronic condition requiring the use of narcotics. How much different will the first appointment be compared to a normal prenatal check up? i will be 20 weeks when i see him. and has anyone has any expeirence with narcotics during pregnancy. my midwife scared me when she sent me to this guy and also said baby will probably have to spend time in the NICU.