But a newborn baby also gets helpful substances from the colostrum, your first milk. This is a thin yellowish fluid very rich in antibodies, nutrients, and other substances your newborn needs. By the time your infant is 6 months old, his or her immune system will begin making more antibodies to fight disease. If you have a family history of allergies, you have a special reason to nurse your baby. A baby is rarely, if ever, allergic to the mother's milk.
Many babies are allergic to cow's milk, which is in infant formulas.
The protein in cow's milk is not like that in the baby's system, and about 7 percent of babies react to these proteins. They may have diarrhea, vomiting, stomach pain, or skin rashes. Breast-fed babies also have fewer allergies in later childhood and adulthood. You may hear about a baby that is allergic to his or her mother's milk. However, this is a not a true allergy to the breast milk.