[Immunologic and ethologic aspects of breast feeding].

Epidemiological studies have shown a marked protective effect of mother's milk (mostly against severe gastrointestinal infections) only under unfavorable conditions. Obviously functional antibodies are formed only in response to life-threatening infections which are rare in conditions of good hygiene. From studies on the ontogeny of the immune system it is becoming increasingly clear that the mother protects her infant within a common enteromammary system, mother and infant thus forming a nutritional and immunological dyad. Specific and nonspecific defense mechanisms of mother's milk are described. Whenever possible, infants should be breast-fed exclusively for 4 months. Breast-feeding should and can be promoted. Around day 5 fully nursing mothers today reach the same amounts of milk as 100 years ago.