▴ 그림 4-6. 모유수유를 할 때 아기의 입과 유방과 젖꼭지의 상관관계도
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
Copyright drleepediatrics.com 2/27/2026
Advantages of Breast Milk and Breastfeeding
For further information, please visit “drleepediatrics.com” and then use the search function.
For further information, please visit “drleepediatrics.com” and then use the search function.
● We have previously discussed the benefits of breast milk and breastfeeding. Let us now explore in greater detail the specific advantages of raising an infant through breastfeeding.
● The temperature of breast milk is always ideal, making it ready for the baby to consume immediately, anytime and anywhere.
● When raising an infant on formula, one must thoroughly wash the baby bottle, nipple, cap, and other components before each feeding.
● At times, these bottles and nipples must also be sterilized in boiling water. Furthermore, the temperature of the formula must be adjusted to a suitable level for consumption. With breastfeeding, there is no need to wash or sterilize bottles and other feeding equipment.
● Formula can be susceptible to contamination by pathogens—such as bacteria and viruses—at any point prior to the moment it is prepared for feeding.
● During breastfeeding, external bacteria, viruses, and other types of pathogens present on the nursing mother’s body do not easily contaminate the milk being consumed by the infant. (Refer to: Contraindications for Breastfeeding)
● Infants raised on breast milk are significantly less likely to contract infectious diseases caused by bacteria, viruses, and other pathogens compared to infants raised on formula.
● Additionally, they are less susceptible to infectious diseases, digestive disorders, allergic gastroenteritis, and various other types of illnesses. ● Child-rearing and medical expenses are reduced; furthermore, the need for hospital visits and the likelihood of requiring inpatient hospital treatment are significantly lower.
● Infants raised on breast milk are less susceptible to viral gastroenteritis, respiratory tract infections, middle ear infections (otitis media), diarrhea, bacterial meningitis, urinary tract infections, and various other types of pathogen-related illnesses.
● Breast milk is more easily digestible than infant formula.
▴ Figure 4-2. Raising an infant through breastfeeding offers a multitude of benefits and advantages for the baby. The physical “contact love”—generated when the mother’s skin touches the baby’s skin during nursing—combined with the intense, focused attention and care provided by the mother, is mutually beneficial to both the infant and the mother. Yet, this profound reality often goes unnoticed or is simply overlooked. A nursing infant receives the mother’s “eye-contact love,” and the mother, in turn, receives that same “eye-contact love” from her baby. This unique form of love is a bond that arises exclusively between a nursing infant and a breastfeeding mother during the act of nursing.
Copyright ⓒ 2013 John Sangwon Lee, M.D. FAAP
● Breast milk protects the infant by significantly reducing their susceptibility to various diseases.
● Infants raised on breast milk are far less likely to develop allergic conditions—such as allergic rhinitis, allergic gastrointestinal disorders, bronchial asthma, and atopic dermatitis—compared to infants raised on infant formula.
● Infants fed breast milk experience fewer instances of infantile colic and constipation compared to those fed infant formula.
● While breastfed babies can still develop allergic conditions, such conditions occur far more frequently in babies raised on artificial formulas containing milk or soy proteins.
● Breast milk contains various anti-pathogenic factors—such as immunoglobulins (including IgA), white blood cells, macrophages, complement proteins, lactoferrin, and lysozyme—as well as other biochemical substances capable of destroying bacteria, viruses, and other pathogens upon invasion; these components, however, are absent in artificial formulas. Consequently, breastfed babies are less susceptible to various infectious diseases, including otitis media, gastroenteritis, sepsis, pneumonia, and urinary tract infections.
● Although modern artificial formulas are now fortified with DHA and ARA—nutrients essential for enhancing brain and eye function—breast milk naturally contains these components in ample quantities.
● Breast milk also contains various other biochemical substances that promote physical growth and development.
● Breast milk contains biochemical substances capable of helping to prevent cancer.
● It contains hormones that stimulate growth and development.
● Children raised on artificial formulas tend to have lower IQ scores than those who were breastfed and are at a higher risk of developing learning disabilities.
● Regardless of how diligently prenatal care and education are practiced during pregnancy, children raised on artificial formulas rather than breast milk tend to have lower IQ scores.
● Children raised on artificial formulas tend to overeat and gain weight more easily; they are more prone to developing childhood obesity, which often leads to adult obesity.
● The incidence of Type 1 and Type 2 diabetes is lower in children who were breastfed.
● The incidence of metabolic disorders—including leukemia, lymphoma, Hodgkin’s disease, hypercholesterolemia, hyperlipidemia, and hyperlipoproteinemia—is lower in children who were breastfed.
▴ Photo 4-3. Observe the gaze of the nursing baby! Note the loving eye contact between mother and baby! It is precisely through this loving eye contact that the bond of love between mother and child is firmly established. This loving bond is formed even more securely during breastfeeding.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
▴ Photo 4-4. Observe the gaze of the nursing baby! Note the loving eye contact between mother and baby! It is precisely through this loving eye contact that the bond of love between mother and child is formed even more securely.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
▴ Photo 4-5. Observe the loving physical contact of the nursing baby! Note the loving physical contact between the mother’s body and the baby! It is precisely through this loving physical contact that the bond of love between mother and child is formed even more securely.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
▴ Photo 4-6. Observe the physical contact of the nursing baby! Note the loving physical contact between the mother’s body and the baby! It is precisely through this loving physical contact that the bond of love between mother and child is formed even more securely. Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
● Children raised on formula have a higher incidence of dental disorders—such as cavities and malocclusion—as well as impaired facial muscle development, compared to children raised on breast milk.
● *Bifidobacterium lactis* accounts for 80–90% of the resident bacterial population within the gastrointestinal tracts of breastfed infants.
● The *Bifidobacterium* colonies in the gastrointestinal tracts of breastfed infants serve to inhibit the growth of pathogenic bacteria and promote the production of IgA antibodies within the intestinal mucosal lining.
● Consequently, infants raised on breast milk are less susceptible to bacterial gastroenteritis caused by pathogenic bacterial infections.
● Furthermore, *Bifidobacterium* promotes the growth and development of breastfed infants. For this reason, *Bifidobacterium lactis* is now frequently added to infant formulas during their preparation.
● The breast milk of a healthy nursing mother—who has consumed a balanced diet providing sufficient protein, carbohydrates, fats, vitamins, water, and minerals—contains all the nutrients necessary for an infant’s normal growth and development during the first six months of life.
● While an infant fed formula can certainly thrive if the mother holds the baby tenderly and lovingly in her arms during feeding, this experience cannot compare to the physical intimacy and love an infant feels when nursing directly from the breast—making contact with the mother’s skin and latching onto her warm nipple.
● When a mother holds her baby in her arms to breastfeed, the baby senses that they are receiving an abundance of love—expressed through eye contact, physical touch, and focused, undivided attention and care.
● During the act of breastfeeding, maternal hormones (often referred to as “mom hormones”) are released within the mother’s body. These hormones play a vital role in enabling the nursing infant to deeply sense their mother’s love; they also serve to strengthen the maternal-infant bond and foster a greater sense of psychological and emotional stability in the baby. This hormone is Oxytocin.
● By directly breastfeeding her child, a mother can gain a heightened sense of confidence in her ability to raise her child to be healthier, smarter, and well-adjusted.
▴ Photo 4-7. There are many additional items required for formula feeding.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
● The breastfeeding mother, the father, and the baby all experience greater mental and physical stability. The parent-child bond (bonding) between the parents and the baby is strengthened even further.
● During the period of breastfeeding, the physical and mental changes—as well as the fatigue—resulting from pregnancy and childbirth, along with the changes in the uterus, can return to normal more quickly.
● Breastfeeding can serve as a natural form of contraception.
● Breastfeeding acts as a weight-loss aid.
● The mother’s weight, which increased during pregnancy, returns to her pre-pregnancy weight more quickly and easily.
● Finally, breast milk is the best, most ideal, and most complete natural food source for a baby.
● Breast milk is the greatest gift of love that a mother and father can give to their child. Raising a baby through breastfeeding promotes the mental, emotional, and physical health not only of the nursing mother, the father, and the baby, but also of the family, the community, and the nation as a whole.
● Breastfeeding is economical.
● It serves as the ultimate tonic for the lifelong health and well-being of the nursing child.
▴ Figure 4-1. In a mother who does not breastfeed after childbirth, the uterus receives less influence from the hormone oxytocin; consequently, it contracts and recovers slowly.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
▴ Figure 4-2. In a mother who breastfeeds after childbirth, the uterus is influenced by the hormone progesterone; consequently, it contracts and recovers more quickly. Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
● Recently, advertisements have appeared claiming that infant formula can be made to be “almost identical to breast milk.” However, no matter how advanced science becomes, it is impossible to create a formula that is exactly the same as breast milk.
● Problems can arise during the processes of preparing, selling, purchasing, and storing infant formula. Bacteria may contaminate the formula while it is being prepared for feeding. One might add too little or too much water compared to the recommended amount, or feed the baby a formula made with inappropriate ingredients.
● Of course, during breastfeeding, there is a possibility of contamination by pathogens—such as bacteria—present on or within the nursing mother’s body. However, barring exceptional circumstances, the likelihood of an infant contracting an infection from the mother during breastfeeding is extremely low.
● The unique emotional connection shared between mother and baby differs vastly depending on whether the baby is fed formula or breast milk. The sensation of being cradled in a mother’s warm embrace while suckling at her warm nipple is likely a world apart from the sensation of suckling on a bottle nipple.
● Unfortunately, many new mothers today leave the hospital delivery room and drive themselves home—often without having fully recovered from childbirth or having undergone proper postpartum care. Mothers who choose to feed their babies formula often find themselves traveling from one shopping center to another to purchase formula, bottles, and other feeding supplies.
● Nowadays, due to various issues—including financial and domestic concerns—many new mothers are unable to obtain adequate physical and mental rest after childbirth and must return to their full-time jobs. Given these circumstances, many mothers—despite being well aware of the benefits of breastfeeding—find themselves compelled by necessity to raise their beloved babies using infant formula instead.
● This describes the unfortunate reality of child-rearing today—a situation that affects not only growing children but also parents (particularly breastfeeding mothers), and indeed nations across the globe.
● There is no doubt that raising an infant through breastfeeding is the most ideal approach. Furthermore, it goes without saying that breast milk constitutes the ultimate natural source of nutrition.
● In recent times, the American Academy of Pediatrics, the U.S. federal government, and various organizations dedicated to promoting breastfeeding have all joined forces to support policies aimed at increasing breastfeeding rates.
● In particular, non-profit organizations involved in promoting pediatric health—such as medical schools and maternal and child health departments—as well as pediatric specialists and nurses who address children’s health issues, strongly advocate for active participation in these breastfeeding promotion initiatives.
● Before delivery, the physician who is slated to become the newborn’s primary pediatrician typically explains the benefits of breastfeeding to expectant mothers. Furthermore, rather than simply offering parents a choice between formula feeding and breastfeeding after the baby is born, there is a collective effort to encourage *all* parents to breastfeed their newborns.
● Finally, if anyone were to ask me what the very best gift is that parents can give their newborn baby, I would answer without hesitation: “Breastfeeding.”
● Of course—breast milk, accompanied by love!
The following is a sample Q&A session from an online pediatric health consultation service, covering the topics of “Breastfeeding, Breast Anatomy, and the Breastfeeding Hormone Prolactin.”
Q&A: Breastfeeding, Breast Anatomy,
and the Breastfeeding Hormone Prolactin—100 Questions and Answers
Q.
What are breasts?
A.
The mammary glands (or breasts) are exocrine glands responsible for producing breast milk. They constitute a part of the female reproductive system. The breast is situated within the subcutaneous tissue of the anterior chest, positioned between the 2nd and 6th ribs, and bounded by the pectoralis major muscle, the sternum, and the axilla. A nipple is located at the center of the breast. The nipple is also referred to as the *papilla mammae*. There is one nipple on each breast. The area of skin surrounding the base of the nipple is known as the areola. The areola contains Montgomery’s glands, which secrete sebum. (Refer to Figure 22-41.)
Q.
What is the internal structure of the breast?
A.
Within a single breast, there are 15 to 20 mammary lobes. Each mammary lobe contains numerous mammary glands (alveolar glands).
These alveolar glands connect to alveolar ducts. The alveolar ducts lead into dilated sections known as lactiferous sinuses (ampullae). These sinuses, in turn, connect to lactiferous ducts. The lactiferous ducts open out through the pores at the tip of the nipple. Milk is released through these pores in the nipple. (Refer to the diagram of the breast.)
Q.
What is the pathway of milk production and release in the breast?
A.
When an infant nurses—sucking on the nipple and stimulating the areola—nerve impulses are transmitted to the hypothalamus in the brain. The hypothalamus then sends a signal to the posterior pituitary gland, triggering the secretion of oxytocin (Pitocin). Oxytocin stimulates the myoepithelial cells surrounding the alveolar glands, causing milk (breast milk) to be ejected from the glands. The milk then flows through the alveolar ducts, the lactiferous sinuses, and the lactiferous ducts, finally passing through the nipple and out via the pores at its tip. Connective tissue and adipose tissue are situated between the individual mammary lobes.
Q.
How do breasts develop?
A.
Prior to puberty, the breast structures of boys and girls are nearly identical.
Once puberty begins, the mammary glands and alveolar ducts develop and enlarge under the influence of female hormones—specifically estrogen and progesterone—secreted by the corpus luteum in the ovaries. Additionally, adipose tissue accumulates within the breast. Consequently, the breasts of girls undergoing puberty develop and grow into a shapely form.
▴ Photo 4-8. There are several small, prominent nodules located on the areola (the pigmented area surrounding the nipple). These nodules are known as Montgomery’s tubercles. Inside these tubercles lie the Montgomery glands. These glands secrete a cream-like, lubricating sebum.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
▴ Photo 4-9. Breast milk is naturally at an appropriate temperature, making it ready for consumption at any time without the need for warming. In this photo, the tips of the Montgomery’s tubercles located on the areola are clearly visible.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
Q.
I’ve heard that pregnancy brings about changes in the breasts as well—is that true?
A.
● When a woman becomes pregnant, many significant physical changes occur throughout her body.
● Among these, the most distinct and prominent physical changes are those that take place in the uterus and the breasts.
● Regardless of whether the unborn baby will eventually be breastfed or formula-fed, the pregnant woman’s body prepares to ensure her precious future child can receive adequate nourishment and grow up healthy; specifically, the acinar glands, milk-secreting cells, and the entire milk duct system within the breasts undergo development.
● Inside the breasts, the lactiferous ducts (secretory ducts of the acinar glands), lactiferous sinuses (ampullae), and milk ducts develop vigorously; additionally, the nipples enlarge, fatty tissue accumulates within the breasts, and the breasts as a whole increase in size.
● The Montgomery glands located on the areola also develop and produce sebum, ensuring that every aspect of the breast functions smoothly to facilitate convenient breastfeeding.
● During the initial period when the breasts are growing and becoming firmer, you may experience some tingling sensations or mild pain. In particular, contact with the nipple can be quite painful.
● Each breast contains 15 to 20 breast lobes.
● Each breast lobe consists of several smaller breast lobules,
● and these breast lobules are further subdivided.
● Within these breast lobules are the milk-producing cells.
● These milk-producing cells cluster together to form milk glands (acinar glands).
● These milk glands are also referred to as acinar glands or mammary glands.
● The ducts through which the milk produced in the glands flows are called acinar ducts. The collective network of these ducts—both large and small—is referred to as the acinar duct system. (Refer to the Breast Diagram.)
● The internal breast cavities where milk secreted by the glands accumulates—prior to the baby nursing at the nipple—are known as lactiferous sinuses or ampullae. Immediately upon conception, the tissues of this internal milk-secreting system within the breast begin to progressively enlarge and develop. Furthermore, the functional activity of the breast continues to heighten—sometimes noticeably, sometimes imperceptibly—right up until the moment of delivery.
● During pregnancy, the placenta secretes an “antiprolactin hormone.” Through the action of this hormone, prolactin is prevented from stimulating the milk-secreting cells of the acinar glands, thereby inhibiting milk secretion. However, immediately after the baby is born and the placenta is expelled from the uterus, prolactin begins to stimulate these milk-secreting cells, and the cells commence milk production. Nevertheless, it typically takes one to two days for prolactin to begin functioning at full capacity following delivery.
▴ Figure 4-3. Milk secretion, cervical dilation, prolactin (the milk-stimulating hormone), oxytocin (the hormone that releases milk into the breast ducts), prolactin secretion triggered by nipple stimulation, and prolactin-inhibiting hormone.
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP
Q. How do breasts produce milk?
A.
When an infant suckles at the nipple, the peripheral nerves located in the nipple and areola are stimulated. At this moment, the signal indicating that the infant is suckling is transmitted via neural impulses to the hypothalamus in the nursing mother’s brain.
From the hypothalamus, these neural impulses are relayed to the posterior lobe of the nursing mother’s pituitary gland.
The hormone oxytocin (also known as Pitocin) is secreted from the posterior lobe of the pituitary gland. This oxytocin hormone:
Stimulates the myoepithelial cells surrounding the acinar cells (milk-producing glands), thereby causing milk to be released into the acinar ducts.
Stimulates the acinar duct system—specifically the milk ducts—to facilitate the flow of milk (which has already been produced by the breast’s secretory cells) from within the breast toward the nipple.
Simultaneously, the neural impulses generated by the act of suckling are transmitted to the nursing mother’s hypothalamus and subsequently relayed to the anterior lobe of the pituitary gland.
The hormone prolactin is secreted from the anterior lobe of the nursing mother’s pituitary gland. This prolactin hormone stimulates the milk-secreting cells (lactocytes) within the breast, thereby promoting milk production. Concurrently, blood circulation within the breasts becomes more vigorous, the fatty tissue within the breasts develops further, and fat accumulates to a greater extent.
The veins located in the subcutaneous tissue of the breasts enlarge to the point where they become easily visible to the naked eye through the skin layer.
Because the breasts increase in size during pregnancy, stretch marks (striae gravidarum) may appear on the skin layer of the breasts.
After childbirth, when the baby suckles at the breast, nerve impulses are transmitted to the hypothalamus and subsequently to the posterior pituitary gland.
Oxytocin is then secreted from the posterior pituitary gland, triggering the release of breast milk. During pregnancy, however—due to the secretion of prolactin-inhibiting hormone by the placenta—prolactin is unable to stimulate the breasts until after the baby is born.
As one studies these various physiological processes, it becomes apparent that the biological mechanisms of our bodies are designed to function much like the intricate circuitry of a computer chip.
Q. If a creamy substance appears on the nipples and areolae during pregnancy, should it be washed off?
A.
During pregnancy, the nipples typically double in size compared to their normal state, and there are approximately 15 to 20 milk-secreting pores located at the tips of the nipples.
The areola—the pigmented area surrounding the base of the nipple—also doubles in size. The color of both the nipple and the areola changes to a deep brownish-black or a dark pink hue.
It is believed that this change in color serves a biological purpose: to make the nipple and areola easily visible and locatable for a nursing infant.
The areola is also naturally dotted with several small bumps known as Montgomery’s glands (or tubercles). Within the Montgomery tubercles lie the Montgomery glands; these glands secrete a cream-like, lubricating sebum that softens the areola and nipple, thereby preventing them from cracking or fissuring during breastfeeding.
In essence, the mechanism is much like oiling a machine to ensure it runs smoothly.
Throughout pregnancy and during the postpartum breastfeeding period, this lubricating sebum serves to protect the nipple and areola.
You should not wash away the cream-like lubricating sebum secreted by the Montgomery glands with soap. Furthermore, there is no specific need to apply topical creams to the nipple or areola.
Q. My breasts are on the smaller side; will I be able to produce enough breast milk for my baby?
A.
There is significant variation in breast size and shape among pregnant women.
Regardless of whether breasts are quite large or small, sagging or firm, every mother’s breasts are capable of producing a sufficient quantity of milk to nourish and support the growth of one—or even two—babies simultaneously.
From the perspective of a pediatrician, the ultimate purpose of the breast is to provide the baby with a sense of security and comfort, and to secrete an ample supply of warm breast milk to ensure the baby can feed and grow up healthy.
Around the fifth or sixth month of pregnancy, a few drops of clear fluid may begin to leak from the multiple milk ducts located in the nipple. This fluid is a form of colostrum. It is also sometimes referred to as “early milk.”
▴ Figure 4-4. The Breast and Areola
Copyright ⓒ 2011 John Sangwon Lee, MD, FAAP