For a time in this century, breast-feeding was largely abandoned in affluent countries in favor of bottles. The use of special formula of cow's milk, in bottles, also became widespread in developing nations. Pediatricians are trying to reverse this trend and they are encouraging mothers to give their babies the advantages of breast milk for some time, even if only for a few weeks. More and more, mothers are opting to breast feed the old fashioned way in order to give their babies the physiscal and emotional advantages of natural breast milk. A chief advantage of nursing is that, not only does human breast milk give the baby some digestible milk proteins, but breast milk protects against infections such as gastroenteritis and pneumonia during the first few months of life when the baby's own immune system is immature.
Immunity is passed from mother to baby through the milk.
Breast-fed babies are also thought less likely to become overweight. There is some speculation that breast- feeding may also protect against heart disease in later life. It is also theorized that babies who have non-human milk early in life are more liable to develop allergies. Nursing also stimulates release of a hormone from the hypothalamus in the brain, which aids the shrinking of the uterus back to normal size following childbirth. Breast size is immaterial to successful feeding.