Natural selection: organisms with certain inherited traits that are more likely to survive and reproduce than others.
These favorable traits can give an organism an advantage by giving them a higher chance of survival and reproduction. Darwin called this, "survival of the fittest"
Hemoglobin in the baby is less than the normal. Nursing should includes the information such as avoid cow milk as it does not contain iron. Fortified milk with iron, solid food with iron fortified baby cereal mixed with breast milk should be given to the baby to increase the hemoglobin level to normal.