Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Breathing difficulty, inability to wake the baby, seizure-like activity, marked limpness, or unusual stiffness requires urgent or emergency care.
Seek prompt advice for worsening jaundice, poor feeding, unusual sleepiness, or fewer wet diapers.
A newborn's follow-up plan depends on the bilirubin result before discharge, age at discharge, gestational age, feeding, weight change, and other risks.
Follow-up may include a bilirubin test, jaundice examination, feeding assessment, and weight check.
After a transfusion reaction, follow-up may include blood counts, kidney function tests, and review by the transfusion service.
The reaction should be documented in the medical record.
Tell clinicians about it before future transfusions, although standard testing and identity checks will still be required.
The article also says
After phototherapy, bilirubin may need to be checked again because it can rebound.
Babies with known or suspected hemolysis may need later blood counts to detect anemia.
Keep all recommended appointments even if the baby looks well.
Every sign above is quoted from the sofidex article on ABO incompatibility. If you are not sure, err upward — it is always reasonable to be checked.