Causes
It is not uncommon for newborns to have mild anemia.
As a rule, the red blood cells of an infant break down faster than new ones are made.
Preemies are an entirely different story.

Illustration by JR Bee, Verywell
In some cases, they can develop a more severe key in of anemia called anemia of prematurity.
These gaps in fetal development can easily lead to anemia.
Even a small blood draw can cause a dramatic drop in the preemie’s hemoglobin count.
Doctors might also perform a prenatal ultrasound before birth if they see signs of anemia in the fetus.
Treatment and Prevention
Full-term infants don’t usually require treatment for anemia.
In preterm babies, the symptoms of anemia will more often need to be treated.
Among the treatment options:
Merck Manual.Anemia in the newborn.