whether or not nursing is planned. the female breasts (with exceptions) secrete a milky fluid called colostrum. Colostrum appears usually after the sixteenth week of gestation. This fluid is thicker and yellower than later milk and somewhat different chemically, but both colostrum and the later milk come from the mammary gland and are valuable for nourishment of the baby.
The biological changes that lead to secretion of milk are not known totally or exactly, but a decline in the levels of progesterone and estrogen appears to accompany a rise in the level of a pituitary hormone called frrolaciin or luteotropin, known as the lactogenic hormone from its influence on milk production. Prolamin activity is high in the blood of lactating women, and in certain complicated experiments prolactin has been shown to produce secretion and breast engorgement artificially.
The true milk appears from twenty-four to ninety-six hours after delivery. “coming in” so suddenly that many women are confident they could tell the exact moment. Others who have been breast-feeding from birth are not so sure. however, and it may be that the sensation of “coming in” is no more than a feeling that the breasts are too full. The letdown reflex is the psychosomatic mechanism involved in expelling the milk that has been secreted in the mammary glands.
This milk is stored in the alveoli, tiny sacs in the breast surrounded by special cells that contract as muscles do. The full process of milk expulsion can be described as follows: sucking stimulates nerves in the breast. and the impulses are carried to the pituitary gland at the base of the brain.in commercial preparation as Pitocin). The oxytocin reaches the breast by way of the bloodstream and acts on the contractile cells. These cells squeeze the milk out of the alveoli into large ducts leading to the nipple. The baby’s sucking. of course, then empties the ducts. The letdown phase of this total process refers to the expulsion of the milk from the alveoli. Other signs of die letdown reflex are strong contractions in the uterus.
The oxytocin in the bloodstream acts on the uterine muscles as well as the tiny muscles in the breast. These uterine contractions, while sometimes painful at first, are a sign that the mother is letting down her milk and that breast feeding is working well. After several days the action of the oxytocin will have served its purpose. The utenis will have clamped down and become small. Thereafter there will be no uterine cramps or afterpains. The letdown reflex is easily inhibited.
When a mother is frightened or upset, she does not let down her milk as well. The milk is in the breast, but the baby cannot get it easily. In one experiment, inhibited mothers, after nursing their babies and being pumped by machine, received oxytocin by injection to set off the letdown reflex artificially. Mothers who had not had enough milk for their babies finally produced. and it was found that almost half their milk had not been avail-able to the baby or the milking machine.
Fortunately. oxytocin can now be given by nasal spray instead of needle. Some doctors prescribe it to help mothers let down their milk when hospital routines disturb them or. later, when something at home upsets them. A tingling in the breast follows the squirt of spray and then milk begins to flow. Newton and Newton have listed four symptoms of letdown:
I. The mother feels cramps or lower abdominal pain while nursing. (Oxytocin causes uterine contractions.)
2. Milk drips from the breast not being sucked. (Cell contractions stimulated by oxytocin are forcing milk from the alveoli.)
3. The breasts drip at expectation or sight of the baby. (The reflex has been established at previous feedings.)
4. Nipple pain ceases after the baby has sucked for a few seconds. (Sucking causes back pressure on .the empty ducts: letdown fills the vacuum with milk, relieving the pressure and pain.) mothers.
Among mothers whose interest in breastfeeding is wavering from the start, the distractions of the usual hospital surroundings may be enough to inhibit the letdown reflex. In pregnancy the breasts become larger in preparation for breastfeeding, and the nipples grow darker. Nature has provided for the nipples to keep themselves partially sterile. Sweat mixed with the oily secretions of the skin has an antibacterial action, and the nipple has the largest sweat glands of all.
Further. newly secreted human milk is reported to have an antibacterial action. Thus, the nipples are ready for sucking whenever the baby needs comfort or food. Although a few drops of fluid hom the breast often appear in the latter days of pregnancy, the big boost in secretion comes at birth. The breasts begin to fill up. How long it takes fur the milk supply to be ample for the baby depends on how much stickling is permitted during the first few days, as well as on individual factors.
An experienced nursing mother who can have her baby in the room with her from birth and who suckles him for hours a day may find the baby gaining weight by the second day, especially if he is very vigorous and alert. But in the usual situation even with rooming-in, milk may not begin to appear in quantity until the third or fourth day. This delay is nothing to worry about. Babies are expected to lose some weight the first few days and most arc a bit poky in the beginning, especially if they have received analgesic drugs transplacentally prior to birth. About the time the milk collies in. the breast may become firm, full, and tender.
This is normal. In extreme cases, fortunately rare, there may be fever and aching all over the body. as well as localized pain in the breast. These are symptoms of extreme engorgement, a condition not common when the breasts have been kept empty by frequent, vigorous nursing periods. Even with extreme engorgement. most of the discomfort goes away after a day or two. Wet packs of towels wrung out in hot tap water seem to help when placed on the sore breasts. A bra that gives good support is helpful.