Newborns are protected from infections by breast milk. The first secretion right after giving birth is almost clear and yellow in color, different from the following so-called breast milk. It is called colostrum1 and the normal breast milk is called mature milk. Colostrum contains more protein, less fat and sugar than breast milk. Most of the proteins are special secretory immunoglobulins called IgA2.
IgA, of course, function as antibodies, which are made by infections experienced by mothers, just like IgG given through placentas. However, the antibiotic value of IgA is slightly different in pattern from that of IgG; the value tends to be higher against infectious factors like intestinal bacteria and viruses. With special molecules attached, they become secretory IgA, so that they are not destroyed in the stomach.
In the areas of poor hygiene, breast-feeding makes a big difference in the disease rate3 and mortality rate of newborns and infants by infections. In particular, breast-fed babies suffer much less from diarrhea or digestive tract infections. It is believed that the antibodies in secretory IgA in the colostrum are applied on the mucosa of digestive tracts and prevent their infections.
On the contrary, in case of animals like cattle that have polyptychial (multilayered) placentas, immunoglobulin can not be transferred to fetuses through them. If newborns fail to take colostrum, they are usually killed by infections.
Hospitals That Do Not Give the First Bath to Newborns
The body surface of a newborn is covered with vernix caseosa4. It is not certain whether this is made by mothers, discharged into amniotic fluid and attaches to the skin of the fetus, or something secreted from the skin of the fetus. Nowadays the latter theory seems to be more dominant.
A thin film of vernix caseosa sticks to a newborn's soft skin and prevents attachment of microbe to the skin. This makes mechanism of phylaxis5 that prevents bacterial invasion as a mechanical barrier6. Its chemical ingredients, fatty acid in particular, kill bacteria or weaken their viability. For this reason some hospitals in foreign countries, particularly in the developing countries do not give the first bath to newborns. Modern obstetrics and neonatology has promoted the childbirth in a clean delivery room for fear of infection by immature immune functions of newborns and this has dramatically reduced the number of infections. At the same time, however, it has led to less frequent contacts between the mother and her child right after birth.
Babies born in advanced society take their first bath, wrapped in clothes for newborns and sent to a nursery as soon as they meet their mothers. In anesthetic delivery, there are many cases that mothers don't even see their babies, thereby missing an important opportunity to establish a mother-child rapport. Nature protects newborns immunologically in many ways so that they can be held in their mothers' arms safely while fighting with some bacteria.
Slightly viscous milk secreted until the end of the first three days after giving birth, whose color is between water-like clear and semitransparent light-yellow. It usually turns into white and non-transparent mature milk within four or five days.
Colostrum contains more protein and salts than mature milk and their nutritional value is two to three times higher. They also contain colostrum corpuscle, or leucocytes indulging fat globules. It is believed that much salt loosen feces and immunoglobulin, mainly secretory IgA in the colostrum, plays an important role in the immune system of newborns.
2: IgA (immunoglobulin A)
A type of immunoglobulin accounting for about 20% of all the immunoglobulins in the blood serum. Many of them exist in the colostrum.
3: Disease rate
The percentage of people who became sick out of the total number of populations during a certain period of time; normally it is shown that how many people suffered from disease out of 1,000.
4: Vernix caseosa
Mixture of peeled epithelial cells from the skin and secretion from sebaceous glands that covers the body surface of the fetus. It prevents erosion of amniotic fluid and mitigates resistance when the fetus goes through the birth canal at the time of delivery. It starts to appear around the end of the sixth months of pregnancy. Premature fetuses tend to have relatively much vernix caseosa while matured ones have very little of them only on the flexion. In this way it can be an indicator to show the degree of maturity of a fetus.
5: Mechanism of phylaxis
A biological response or immune response in a wide sense to prevent the adhesion or multiplication of, or disinfect, invading pathogenic microbes.
A defense wall or obstacle made of the organs of a human body.
Kobayashi, Noboru (1981). "Wagako wo Mamoru Hahaoya no Menekikotai"
(written in Japanese). Tokyo: Child Research Net. Retrieved Oct. 8, 2004, from the World Wide Web http://www.crn.or.jp/LIBRARY/KOBY/MIRAI/cbs0122.html