The umbilical cord provides oxygen and nutrients for the fetus to develop while in the mother's womb. After birth, the umbilical cord is clamped and cut, leaving an umbilical stump that eventually falls off and heals to form the navel. Normally, the umbilical stump may have a characteristic odor before it falls off. However, if a newborn's navel smells bad after it has fallen off, this may be a problem and the baby needs proper care.