Preterm babies require more protein than their mother's milk can naturally provide. In order for these fragile babies to thrive, fortifier often needs to be added to the milk. The absence of adequate protein supply causes delay in the infant's growth and increase mortality and morbidity.
To address this problem, now in hospitals non-human origin proteins (cow milk proteins) are added to the human milk to enrich its protein value, this procedure is done daily during all first two-three months of life of such infants. These practices have high risk of side-effects (due to non-human origin of proteins).