Babies should receive a pulse oximetry screen (painless test to check the level of oxygen in the blood) before hospital discharge to look for critical congenital heart defects (CCHD).  If your baby gets to go home with you, then the test was initially normal. 

  However, due to expected changes in a baby’s blood circulation in the first few weeks of life, the pulse oximetry cannot detect all CCHDs until a few weeks after birth. These babies (about 2 in every 1,000) can have severe heart complications resulting in poor outcomes and/or death.

  Since some babies with CCHD can look and act perfectly normal at first, parents need to watch and immediately report the common yet vague signs of CCHD.  Reporting cannot wait a few days; reporting must happen soon after noticing signs and symptoms.  The baby will need to see a provider immediately to evaluate for CCHD. A repeat pulse oximetry screening will be very helpful.

Remember this simple mnemonic for the vague signs and symptoms:
   BFF for Life
   B is for breathing.  Your baby’s breathing may be fast or different
   F is for feeding.  Your baby may not feed well
   F is for fussiness.  Your baby may be fussy
   L is for lethargy.  Lethargy means being tired and worn out.  Your baby may appear tired and worn out after       activity/crying.  You may see this in your baby, especially after feeding. 
 
Also, important to note, your baby may sweat with feeding, especially around the head.
These signs/symptoms are not all-inclusive but are considered typical.
 
References
Baby’s First Test. (2018, May 21). https://www.babysfirsttest.org/newborn-screening/conditions/critical-congenital-heart-disease-cchd
Hoffman, J. I. E., & Hons, B. S. (2019). False negative diagnoses of critical congenital heart disease with screening neonatal pulse oximetry. Journal of Neonatal-Perinatal Medicine, (Preprint), 1–5. https://doi.org/10.3233/NPM-190297
McClain, M. R., Hokanson, J. S., Grazel, R., Van Naarden Braun, K., Garg, L. F., Morris, M. R., Moline, K., Urquhart, K., Nance, A., Randall, H., & Sontag, M. K. (2017). Critical congenital heart disease newborn screening implementation: Lessons learned. Maternal and Child Health Journal, 21(6), 1240–1249. https://doi.org/10.1007/s10995-017-2273-4