The decline in breastfeeding has been traced to the social changes brought about by the industrial revolution [7]. In 1880, 95% of all infants were breastfed for two to four years, but as mothers began reporting breastfeeding difficulties, physicians blamed the stress of urban life and the "bad" human milk produced by urban women. These mothers, who were just learning about the germ theory of disease and anxious to protect their babies, began to gratefully rely on "scientific" food rather than that produced by their own bodies [5,8].

To protect breastfeeding women from harassment, states have passed laws that specifically address breastfeeding [15]. As of 2022, all 50 states have passed legislation specifically allowing women to breastfeed in any public or private location, and 31 states exempt breastfeeding from public indecency laws. Thirty states have passed laws related to breastfeeding in the workplace; 22 states exempt breastfeeding mothers from jury duty or allow jury service to be postponed; and 4 states (California, Illinois, Minnesota, Missouri) have implemented or encouraged the development of a breastfeeding awareness education campaign [15,16].

The American Academy of Pediatrics (AAP) policy statement Breastfeeding and the Use of Human Milk has established principles to guide pediatricians and other healthcare professionals in assisting women and children in the initiation and maintenance of breastfeeding [20]. It also has recognized the breastfed infant as the normal "gold" standard against which all research and recommendations for infant feeding should be made. This is a paradigm shift in American scientific thinking. The AAP has recommended exclusive breastfeeding for the infant's first six months of life, followed by continued breastfeeding for one year or longer as complementary foods are introduced. It also has recommended that [20,21,22]:

The American Academy of Pediatrics (AAP) policy statement Breastfeeding and the Use of Human Milk has established principles to guide pediatricians and other healthcare professionals in assisting women and children in the initiation and maintenance of breastfeeding [20]. It also has recognized the breastfed infant as the normal "gold" standard against which all research and recommendations for infant feeding should be made. This is a paradigm shift in American scientific thinking. The AAP has recommended exclusive breastfeeding for the infant's first six months of life, followed by continued breastfeeding for one year or longer as complementary foods are introduced. It also has recommended that [20,21,22]:

These statistics have generated concern among researchers and policy makers. All major medical societies in the United States, including the AAP, have recommended breastfeeding for as long as possible in infancy in order to improve childhood survival rates. The World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) guidelines have recommended extending breastfeeding for a minimum of two years. This recommendation is supported by research, which has shown a 21% decrease in U.S. infant mortality in breastfed infants [21]. Exclusive breastfeeding, or human milk feeding for a minimum of six months, provides the greatest level of protection against infantile illnesses.

An objective of Healthy People 2030 is to increase the proportion of U.S. mothers who breastfeed their babies through 6 months of age and who continue to breastfeed their babies through 12 months of age. A review of Healthy People 2030 reported the following progress toward achieving this objective [28]:

In 1991, the WHO and UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which was designed to create change in healthcare facilities. The aim of the BFHI was to foster an environment that supports, protects, and promotes breastfeeding, as indicated by the WHO's International Code of Marketing of Breast-milk Substitutes[40,41]. The process for obtaining certification as a baby-friendly hospital has been established by UNICEF in collaboration with national governments worldwide. UNICEF's Ten Steps to Successful Breastfeeding has been the basis for evaluating hospitals and healthcare facilities for participation as a designated baby-friendly facility (Table 3). A 2000 statement by the United Nations (UN) regarding the "rights of the child" has been linked to the BFHI. The UN has stated that in order for hospitals with maternity units to be designated "child friendly" they must first fully implement the Ten Steps to Successful Breastfeeding and be accredited by WHO/UNICEF as baby friendly [42]. The Ten Steps to Successful Breastfeeding and the BFHI have been shown to be effective measures to increase breastfeeding initiation, duration, and exclusivity [43,44].

In 1991, the WHO and UNICEF launched the Baby-Friendly Hospital Initiative (BFHI), which was designed to create change in healthcare facilities. The aim of the BFHI was to foster an environment that supports, protects, and promotes breastfeeding, as indicated by the WHO's International Code of Marketing of Breast-milk Substitutes[40,41]. The process for obtaining certification as a baby-friendly hospital has been established by UNICEF in collaboration with national governments worldwide. UNICEF's Ten Steps to Successful Breastfeeding has been the basis for evaluating hospitals and healthcare facilities for participation as a designated baby-friendly facility (Table 3). A 2000 statement by the United Nations (UN) regarding the "rights of the child" has been linked to the BFHI. The UN has stated that in order for hospitals with maternity units to be designated "child friendly" they must first fully implement the Ten Steps to Successful Breastfeeding and be accredited by WHO/UNICEF as baby friendly [42]. The Ten Steps to Successful Breastfeeding and the BFHI have been shown to be effective measures to increase breastfeeding initiation, duration, and exclusivity [43,44].

Known risks associated with ABM include [1,5,20,82,85,86,87,88]:

Lipids provide 50% of the energy content in human milk and are its most variable component. The fat content of mature milk is approximately 3.8%. Fat content varies from one mother to another, from early to late lactation, from feeding to feeding, and within individual feedings. The total fat content varies from 22 g/L to 62 g/L and is independent of the frequency of breastfeeding. Maternal diet affects the constituents of the lipids but not the total fat content. When a mother's caloric intake is poor, fat is mobilized from maternal fat stores (primarily in the hips and thighs) [2]. The cholesterol level of breast milk remains constant despite manipulation of the mother's cholesterol intake. The lipid fraction of human milk provides essential fatty acids, which are important to proper brain growth. Tissues of breastfed and ABM-fed infants have demonstrated distinctly different plasma fatty acid compositions. Levels of fatty acids in lactating women have been shown to be low, suggesting that their transfer to breast milk occurs at the expense of the maternal stores [2].

The immunoglobulin found in highest concentration in human milk is IgA. The secretory form of IgA (sIgA) lines the gut and respiratory system in adults and is the major component conferring passive immunity to the breastfed infant. It is both synthesized and stored in the breast, reaching levels up to 5 mg/mL in colostrum, then decreasing to 1 mg/mL in mature milk [2]. sIgA is stable in breast milk and not degraded by either gastric acid or digestive enzymes. It provides local immunity by building a lining on the walls of the intestinal tract, the oral pharynx, and the urinary tract, protecting the infant from infection by preventing invasion of organisms through the mucosa. sIgA fights disease without causing inflammation. IgA protects the infant from invasion but does not fully line the gut until the infant is about 6 months of age. It may take months before the infant can manufacture IgA. Bottle-fed infants have few means for battling ingested pathogens until they begin making IgA on their own [2]. Protection through passive immunity continues for as long as the infant is breastfed. A child's immune response is not fully developed until 5 years of age.

Colostrum, known as "liquid gold," is the first milk. It is a mixture of residual cells in the breast and newly formed milk. It is thick and yellow to orange in color with high ash content and higher concentrations of sodium, potassium, chloride, protein, fat-soluble vitamins, and minerals than mature milk. Colostrum also is rich in antibodies that protect the newborn. It has an important laxative effect on the infant bowel that assists in the emptying of meconium. This is important because the retention of meconium may contribute to neonatal jaundice due to reabsorption of its bilirubin content [118].

Stage II of lactogenesis begins with the sudden withdrawal of pregnancy hormones around the time of delivery; it may be defined as the time of copious milk secretion. Stage II is marked by increases in blood flow, oxygen, and glucose as well as sharply increased concentrations of citrate in the breast [122]. The breasts will begin to produce milk independent of infant suckling.

Progesterone antagonism from the placenta enables the prolactin level to rise without subsequent milk production. Progesterone interferes with prolactin's activity on the cell receptor sites in the alveoli of the breast. With the birth of the placenta and the sudden drop in the pregnancy hormones progesterone and estrogen, the elevated prolactin level, in addition to the presence of insulin and cortisol, brings in the milk supply. Prolactin is released in pulses directly related to stimulation of the areola or breast. Prolactin levels decrease as lactation is established, but nursing stimulates prolactin release from the pituitary, which promotes continued milk production [1,2,124,125,126].

The prolactin receptor site theory has raised concern over progesterone-laden birth control methods when they are started within days of the birth. Medroxyprogesterone acetate (Depo-Provera) shots are sometimes given immediately postpartum, while the mother is still in the hospital. If progesterone is an antagonist to prolactin, logic dictates that progesterone shots, implants, and pills can inhibit early establishment of milk production [1]. Detectable amounts of Depo-Provera have been identified in the milk of mothers receiving the drug; however, it does not appear to adversely affect milk composition, quality, or amount [127]. Therefore, the Academy of Breastfeeding Medicine recommends that clinicians advise women that hormonal contraceptive methods may decrease milk supply, especially in the early postpartum period. Additionally, hormonal methods may be discouraged in some circumstances, such as [128]:

It is important to note that the breast never truly empties and that the rate of milk production depends on the rate of milk removal (i.e., the more milk removed by infant demand, the greater the milk production). Research has demonstrated that each breast makes milk slowly or quickly depending on how full or empty it is. A full breast produces milk slowly; an empty breast produces milk more quickly. Therefore, when the mother's breast seems emptiest, it is making milk the fastest. If baby is hungry and nurses vigorously, leaving the breast relatively empty, production speeds up. If baby does not take much milk while feeding, production slows down. Thus, baby's appetite controls mother's milk production. Assuring that baby has access to the breast when hungry allows the baby to regulate milk production [1,2].

Research has indicated that each breast has its own individualized maximum storage capacity, which is not related to breast size. However, mothers with larger breasts have greater storage capacity (the difference between maximum and minimum breast volumes during a 24-hour period) and, as a result, greater flexibility in feeding intervals. Women with smaller breasts can produce as much milk as women with larger breasts, but they must breastfeed more often [2]. This helps explain why cue feeding, rather than strict scheduling, is best for baby and for the mother's milk supply.

If the breasts are not signaled by a suckling infant or breast stimulation within the first 24 to 48 hours postpartum, the result is alveolar distention, tissue congestion, and destruction of alveolar tissue. Distended lactational tissue and tissue congestion may prevent the appropriate hormones from reaching the breast and producing the desired effect of milk synthesis and milk ejection. Some mothers develop a fever if excessive engorgement occurs. A fever as high as 100°F accompanying engorgement in the early postpartum period may be mistaken for postpartum infection. Unrelieved engorgement and over-distention of the alveoli may cause some alveoli to rupture, resulting in partial involution of the breast. Subsequently, complete involution of the breasts may occur in as little as six hours in unrelieved engorgement [131].

The breast is composed of glandular tissue, fibrous tissue, and adipose (fatty) tissue. The relative proportion of each type of tissue changes with a woman's age, menstrual cycle, pregnancy, and nutritional status. The significant structures of the adult female breast include (Figure 1) [2,14,122,133]:

Successful breastfeeding is not automatic, as demonstrated by the failure rate [1]. Women must be educated about breastfeeding to succeed at breastfeeding. Furthermore, the definition of successful breastfeeding is the achievement of the mother's goal for breastfeeding, whatever that may be. For example, if her goal is to nurse for 12 months but she is only able to nurse for 12 days, then she has not achieved her goal.

Women may develop breast lumps at any time. Approximately 29% of cases of breast cancer occurs in women younger than 45 years of age [140]. The average patient is between 32 and 38 years of age [141]. Breast cancer is the most common cancer in pregnant and postpartum women, occurring in about 1 in 3,000 pregnant women; however, this percentage may increase as more women delay childbearing until their mid- to late-30s [141,142,143,144]. The breast changes that accompany pregnancy and lactation often make the mother aware of a lump that she has not felt before. Pregnant and lactating breasts are dense and lumpy. Women may delay treatment because they believe the lump is a disorder of lactation that will remedy itself. Inflammatory breast cancer, the most lethal of localized advanced cancers, often mimics mastitis; however, there are no systemic symptoms [143].

It is important to ask the mother if she has had breast surgery or surgery around the area of the breasts. Breast surgery may adversely affect a mother's ability to nurse by interfering with normal anatomy and neurohormonal pathways.

HIV infection: Although the risk of postpartum HIV infection of the infant remains unclear, studies have indicated that vertical transmission of HIV through breast milk is possible. The AAP has recommended that women who test positive for HIV not breastfeed in order to help prevent transmission of the virus to their infants. The CDC also has recommended that any woman with known HIV infection should be informed about the risks of HIV transmission through breast milk and counseled not to breastfeed. The WHO guidelines have indicated that when the mother is HIV infected, the additional risk of the infant dying if not breast-fed should be compared to the infant's risk of becoming HIV infected through breastfeeding. The mother who is HIV positive and wants her infant to receive human milk may choose to either pump her own milk and have it pasteurized at a local milk bank or hospital or obtain milk from a breast milk bank.

Lack of desire: The woman who has been fully informed of the risks associated with ABM use and who does not wish to breastfeed should not be compelled to nurse her infant.

Human T-cell leukemia virus type I (HTLV-I): This virus is endemic in the West Indies, Africa, and southwestern Japan. Women in the United States with HTLV-I disease should not breastfeed.

Breast cancer: The woman with active breast cancer requires treatment for herself. Women with a history of breast cancer should not be prohibited from breastfeeding. However, the infant should be monitored for appropriate growth, as radiation to the breast causes destruction of the milk-producing glands.

Active hepatitis B infection: Hepatitis B transmission through breastfeeding has not been reported. Infants born to hepatitis B-infected mothers should be immunized with hepatitis B immune globulin immediately after birth, plus given a first dose of human hepatitis B vaccine within 12 hours of birth. With appropriate follow-up immunizations, the baby may nurse.

Hepatitis C: Most patients with hepatitis C are asymptomatic with no traceable transmission route. The greatest risk is chronic active hepatitis C. Infection through breast milk appears to be infrequent.

The word doula comes from ancient Greek, meaning "woman's servant" [119,161]. Throughout history, doulas have supported women through labor and birth and they continue to do so in much of the world today. Doulas provide continuous psychologic encouragement and physical assistance to the mother [7,161]. Doulas provide specific labor support skills, offer guidance and encouragement, assist mothers to cover gaps in their care, build team relationships, and encourage communication between the mother, nursing staff, and medical caregivers [162].

Studies have shown that a doula's presence at birth tends to result in [161,163,164]:

Use of pharmacologic agents for pain relief in labor and the postpartum period may relieve suffering during labor and allow mothers to recover from birth, especially cesarean birth, with minimal interference. However, these agents also may affect the course of labor, the neurobehavioral state of the neonate, and the initiation of breastfeeding. Unmedicated birth followed by immediate skin-to-skin contact between mother and infant leads to the highest likelihood of baby-led breastfeeding initiation. Difficult, medicated labors may lower the rate of breastfeeding success due to the effects on the infant, including depressed or delayed suckling (Table 8) [167,168,169].

Breastfeeding can be unconsciously sabotaged by hospital routines. Newborn policies can have serious effects on lactation and may contribute to maternal engorgement and routine assignment of any cesarean section baby to the nursery for several hours after birth. In addition to ensuring skin-to-skin contact between mother and infant immediately following birth, nursery and postpartum routines that support lactation include [1,2,21,200,202,203,204,205,206,207,208]:

If the infant is correctly latched-on to the breast, the mother will feel a tugging sensation. The first few suckles will be a bit tender as the infant stretches the nipple into the back of the mouth but should not last more than one or two suckles. The nipple remains sensitive for a few days after delivery. Most mothers report mild latch-on pain in the first week that disappears after the first 30 seconds of a feeding. Pain beyond the first minute or so of nursing is a sign of improper latching and should be immediately corrected. Instruct the mother to take a deep breath and release it slowly. If pain persists, she should detach the baby by inserting her finger in the corner of his or her mouth to break the latch and try again. Baby may need to go on and off the breast several times before the latch is correct [209].

Following the initial quiet alert stage after birth, baby goes into a deep sleep, recovering from the rigors of labor. Deep sleep is followed by increased wakefulness and increased nursing demands called "cluster feeding." Mothers often interpret cluster feeding as an indication that their baby is not getting enough milk [2]. This is the prime time during which mothers request supplemental bottles. Anticipatory guidance about these episodes can prevent the mother from assuming her milk is inadequate and giving supplemental bottles. Assure the mother that cluster feeding is normal and that it is actually a series of mini-feedings that are often followed by another period of deep sleep. Mother should be encouraged to catch up on her own sleep between cluster feedings [2].

Although primary failure of lactogenesis is rare, warning signs that require watching include [1,2]:

Jaundice in the newborn is the result of a normal elevation of unconjugated bilirubin and often referred to as "physiologic jaundice of the newborn" [2,221]. This is a common clinical condition that occurs in roughly two-thirds of all newborns. It disappears in about one week in the ABM-fed infant but may persist for several weeks in the breastfed infant. This pattern is known as "breast milk jaundice" [2,230].

Because breast milk jaundice is a prolongation of neonatal jaundice, it is typically identified after the infant has been discharged from the hospital. "Starvation jaundice," however, may be seen as early as the first few days after birth, although not before 24 hours. Starvation jaundice has been observed in infants who have not established adequate feedings. Whether due to maternal or neonatal factors, infants who have not established adequate breastfeeding should not be discharged. Breastfeeding evaluation, encouragement and training for the mother (e.g., positioning, latching), and continuation of breastfeeding to restore fluid and caloric intake should occur [2]. Poor caloric intake and/or dehydration associated with inadequate breastfeeding may contribute to the development of hyperbilirubinemia. Increasing the frequency of nursing decreases the likelihood of subsequent significant hyperbilirubinemia in breastfed infants [222].

Numerous studies have shown that breast/nipple creams do not assist in the prevention or healing of sore nipples. Additionally, many ingredients in breast/nipple cream preparations may be hazardous to the newborn [265]. Breast and nipple creams generally are not recommended for the nursing mother by lactation consultants [2]. Table 12 is a brief list of some commonly used agents and comments on each.

Unfortunately, many women fail to recognize the signs and symptoms of PPD, and when they do, they fail to seek treatment [272]. Women with a history of prior depression, panic disorder, obsessive compulsive disorder, marital problems, premature delivery, premenstrual syndrome, or prior PPD are at highest risk for developing PPD. Additional risk factors include lack of social support, lower income and education, single status, life stress, and unintended pregnancy [271]. The American Academy of Family Physicians has listed the following as warning signs of PPD [273]:

A lactation consultant is a formally trained breastfeeding expert. The International Lactation Consultant Association (ILCA) is the professional association for International Board Certified Lactation Consultants (IBCLCs) and other healthcare professionals who care for breastfeeding families. An IBCLC is a healthcare professional who specializes in the clinical management of breastfeeding. They are certified by the International Board of Lactation Consultant Examiners, under the direction of the U.S. National Commission for Certifying Agencies. IBCLCs work worldwide in a variety of healthcare settings [283].

Consultants come from a variety of backgrounds, and include nurses, educators, and individuals who have counseled breastfeeding women for many years. Hospitals often have a lactation consultant associated with their maternity unit. Training and approach to difficulties may vary slightly among consultants. The one thing that all lactation consultants have in common is the sincere desire to help women toward a successful breastfeeding experience.