When compared to breastfed babies, formula-fed babies have higher incidences of asthma, allergies, childhood diabetes, Gastro-Esophageal Reflux Disease (GERD), obesity, Sudden Infant Death Sydrome (SIDS), and many other disorders and illnesses. A woman who never breastfeeds increases her risks for pre-menopausal breast cancer, ovarian cancer, endometrial cancer, rheumatoid arthritis, and osteoporosis. The American Academy of Pediatrics recommends that all babies be breastfed exclusively to six months, and breastfed in conjunction with healthy table foods at least until one year of age. However, only 65.1% of all American babies are breastfed upon hospital discharge after birth. At 6 months of age, that rate drops to 27%. Why are breastfeeding rates so low?
Breastfeeding rates are low due to the propagation of myths by well-meaning family members and pediatricians. The common battle cry for a formula-feeding mother is “I just couldn't produce enough milk.” She is then patted on the back for trying and handed a bottle. She is often misinformed as to the process of milk production and told to supplement, leading her down the slippery slope of insufficient milk supply. If she had known how the breasts produce milk, she could have solved her supply problem; the purpose of my essay is to inform the reader of the mechanics of milk production.
Inside the breast are alveoli, which are little bags that hold milk and are connected to tube-like ducts. The ducts run down from the alveoli, through the middle of the breast, and end at the nipple. Imagine there's a tree inside of the breast. The alveoli would be the leaves of the tree, and the ducts would be the tree limbs and trunk. Around an alveolus is a band of muscle fibers that contract to empty the alveolus of milk.
Inside the alveolus are special cells, called lactocytes. These absorb nutrients, immunoglobulin, and hormones from the mother's blood stream to compose breast milk. On the walls of the lactocytes are the prolactin receptor sites. The prolactin receptor sites allow prolactin to be absorbed from the blood and enter into the alveoli to stimulate milk production.
Around 16-22 weeks gestation, the mother's body begins producing milk. During this stage, the pituitary gland, the gland located deep in the middle of the brain behind the eyes, increases prolactin levels in the blood stream. The prolactin moves through the blood from the central nervous system into the prolactin receptor sites in the lactocytes. Prolactin then transmits a “message” to the lactocytes to begin production of milk.
Lactocytes make the first milk, a clear yellowish high-protein, mineral-dense fluid called colostrum. Although the breasts now produce colostrum, the milk supply is kept to a minimum due to the pregnancy hormone, progesterone.
Once the mother births her baby, the progesterone levels suddenly drop. This rapid decrease in progesterone signals the breasts to produce more milk, and the next stage begins. If the infant is placed on the mother's stomach directly after birth, he will instinctually creep up the mother's torso and begin suckling on her breast. The nipple stimulation created by the suckling increases the production of two key hormones, prolactin and oxytocin. The lactocytes respond to this boost in prolactin by increasing the volume of milk. However, the milk still needs to leave the alveoli in order for the milk to reach the infant's mouth. Oxytocin is responsible for this process, called milk ejection.
The pituitary gland increases oxytocin levels in the blood when the newborn stimulates the nipples. Oxytocin signals the muscle fibers around the alveoli to contract, squirting the milk out of the alveoli, down through the ducts, and out of the breast through the nipple into a happy baby's mouth. Once an alveolus empties, it exposes the prolactin receptor sites, allowing them to receive prolactin from the bloodstream. The prolactin then increases the amount of milk being produced, so the baby's next meal is ready and waiting.
Until the prolactin rise enough, the breasts produce only a small amount of colostrum. Some health professionals take this as a sign that the breasts are inadequate, and the baby needs a bottle of formula until the milk comes in. This practice is harmful to the supply and demand process implemented by the body.
Up until birth, milk production was stymied by the pregnancy hormone, progesterone. After birth, progesterone levels are much lower, and the baby empties the alveoli at a fast pace, signaling the body to produce more milk. If the infant satisfies his sucking needs and hunger by using a bottle, he does not suck the mother's breast. Thus, the mother's breast does not receive the stimulation needed to increase milk supply.
Until prolactin rates are at adequate levels, the baby is satisfied by colostrum. The milk "comes in" after prolactin rates have dramatically risen. This is around the same time that the milk changes from colostrum to the higher fat mature breast milk. After the milk comes in, milk production becomes dependent on the breasts emptying. When it comes to milk production, the saying goes “use it or lose it.”