Why do hemoglobin levels increase in a newborn baby?

Need for oxygen. in the womb. the high hemoglobin is needed to provide oxygen to the developing fetus. The hemoglobin also is very special in that it holds oxygen very well. Right after birth this HGB is replaced with a more needed regular HGB, that works better in an air environment. The breakdown of this large amount of hemoglobin can cause a problem with jaundice in some babies.