This secondary source (Oddy, W. H. (2001)) presents a literature review of many studies that show the benefits of breastfeeding, especially as it relates to the immune system. There was a correlation in many studies between breast-fed babies and health. The authors shows that babies received anti-bodies from breastfeeding, providing them with short-term immunity through a mechanism known as passive immunity, where the mother passes down secretory immunoglobulin A (sIgA) antibodies (The mechanism behind the presence of slgA is the entero-broncho-mammary pathway for the migration of Iymphocytes).