Merck Manual

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Deborah M. Consolini

, MD, Thomas Jefferson University Hospital

Reviewed/Revised Sep 2023
Topic Resources

Breast milk is the nutrition of choice for young infants. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for a minimum of 6 months and introduction of appropriate solid food from 6 months to 1 year (1 Reference (See also Nutrition in Infants.) Breast milk is the nutrition of choice for young infants. The American Academy of Pediatrics (AAP) recommends exclusive breastfeeding for a minimum of 6 months... read more ). Beyond 1 year, breastfeeding continues for as long as both infant and mother desire, although after 1 year, breastfeeding should complement a full diet of solid foods Solid Foods in Infancy The World Health Organization (WHO) and American Academy of Pediatrics (AAP) recommend exclusive breastfeeding for about 6 months, with introduction of solid foods thereafter. Other organizations... read more and fluids. To encourage breastfeeding, practitioners should begin discussions prenatally, mentioning the multiple advantages:

  • For the child: Nutritional and cognitive advantages and protection against infection, allergies, obesity, Crohn disease, and diabetes

  • For the mother: Reduced fertility during lactation, more rapid return to normal prepartum condition (eg, uterine involution, weight loss), and protection against osteoporosis, obesity, and ovarian and premenopausal breast cancers

Milk production is fully established in primiparas by 72 to 96 hours and earlier in multiparas. The first milk produced is colostrum, a high-calorie, high-protein, thin yellow fluid that is immunoprotective because it is rich in antibodies, lymphocytes, and macrophages; colostrum also stimulates passage of meconium. Subsequent breast milk has the following characteristics:

  • Has a high lactose content, providing a readily available energy source compatible with neonatal enzymes

  • Contains large amounts of vitamin E, an important antioxidant that may help prevent anemia by increasing erythrocyte life span

  • Has a calcium:phosphorus ratio of 2:1, which prevents calcium-deficiency tetany

  • Favorably changes the pH of stools and the intestinal flora, thus protecting against bacterial diarrhea

  • Transfers protective antibodies from mother to infant

  • Contains cholesterol and taurine, which are important for brain growth, regardless of the mother’s diet

  • Is a natural source of omega-3 and omega-6 fatty acids

These fatty acids and their very long-chain polyunsaturated derivatives (LC-PUFAS), arachidonic acid (ARA) and docosahexaenoic acid (DHA), are believed to contribute to the enhanced visual and cognitive outcomes of breastfed compared with formula-fed Formula Feeding The only acceptable alternative to breastfeeding during the first year is formula; water can cause hyponatremia, and whole cow’s milk is not nutritionally complete. Advantages of formula feeding... read more infants. Most commercial formulas are now supplemented with ARA and DHA to more closely resemble breast milk and to reduce these potential developmental differences.

If the mother’s diet is sufficiently diverse, no dietary or vitamin supplementation is needed for the mother or her term breastfed infant. However, to prevent vitamin D deficiency rickets Vitamin D Deficiency and Dependency Inadequate exposure to sunlight predisposes to vitamin D deficiency. Deficiency impairs bone mineralization, causing rickets in children and osteomalacia in adults and possibly contributing... read more , vitamin D 10 mcg (400 units) orally once/day beginning in the first 2 months is given to all infants who are exclusively breastfed. Premature and dark-skinned infants and infants with limited sunlight exposure (residence in northern climates) are especially at risk of vitamin D deficiency. After 6 months, breastfed infants in homes where the water does not have adequate fluoride (supplemental or natural) should be given fluoride drops. Clinicians can obtain information about fluoride content from a local dentist or health department.


Breastfeeding Technique

The mother should use whatever comfortable, relaxed position works best and should support her breast with her hand to ensure that it is centered in the infant’s mouth, minimizing any soreness. The center of the infant’s lower lip should be stimulated with the nipple so that rooting occurs and the mouth opens wide. The infant should be encouraged to take in as much of the breast and areola as possible, placing the lips 2.5 to 4 cm from the base of the nipple. The infant’s tongue then compresses the nipple against the hard palate. Initially, it takes at least 2 minutes for the let-down reflex to occur.

Volume of milk increases as the infant grows and stimulation from suckling increases. Feeding duration is usually determined by the infant.

Some mothers require a breast pump to increase or maintain milk production; in most mothers, a total of 90 minutes/day of breast pumping divided into 6 to 8 sessions produces enough milk for an infant who is not directly breastfed.

The infant should nurse on one breast until the breast softens and suckling slows or stops. The mother can then break suction with a finger before removing the infant from one breast and offering the infant the other breast. In the first days after birth, infants may nurse on only one side; then the mother should alternate sides with each feeding. If the infant tends to fall asleep before adequately nursing, the mother can remove the infant when suckling slows, burp the infant, and move the infant to the other side. This switch keeps the infant awake for feedings and stimulates milk production in both breasts.

Mothers should be encouraged to feed on demand or about every 1½ to 3 hours (8 to 12 feedings/day), a frequency that gradually decreases over time; some neonates < 2500 g may need to feed even more frequently to prevent hypoglycemia. In the first few days, neonates may need to be wakened and stimulated; small infants and late preterm infants Preterm Infants An infant born before 37 weeks of gestation is considered preterm. In 2021 in the United States, 10.48% of births were preterm ( 1), and in 2018, 26.53% of births were early term (significantly... read more should not be allowed to sleep long periods at night. Large full-term infants who are feeding well (as evidenced by stooling pattern) can sleep longer. Eventually, a schedule that allows infants to sleep as long as possible at night is usually best for the infant and family.

Mothers who work outside the home can pump breast milk to maintain milk production while they are separated from their infants. Frequency varies but should approximate the infant’s feeding schedule. Pumped breast milk should be immediately refrigerated if it is to be used within 48 hours and immediately frozen if it is to be used after 48 hours. Refrigerated milk that is not used within 96 hours should be discarded because risk of bacterial contamination is high. Frozen milk should be thawed by placing it in warm water; microwaving is not recommended.

Infant Breastfeeding Complications

A rough assessment of feeding adequacy can be made by daily diaper counts. By age 5 days, a normal neonate wets at least 6 diapers/day and soils at least 4 diapers/day; lower numbers suggest underhydration and undernutrition. Also, stools should have changed from dark meconium at birth to light brown and then yellow. Weight is also a reasonable parameter to follow (see Feeding Problems Feeding Problems If the delivery was uncomplicated and the neonate is alert and healthy, the neonate can be brought to the mother for feeding immediately. Successful breastfeeding is enhanced by putting the... read more ); not attaining growth landmarks suggests undernutrition. Constant fussiness before age 6 weeks (when colic Colic Colic is frequent and extended periods of crying for no discernible reason in an otherwise healthy infant. Although the term colic suggests an intestinal origin, etiology is unknown.... read more may develop unrelated to hunger or thirst) may also indicate underfeeding.

Maternal Breastfeeding Complications

Common maternal complications include breast engorgement, sore nipples, plugged ducts, mastitis, and anxiety.

Breast engorgement, Breast engorgement Clinical manifestations during the puerperium (6-week period after delivery) generally reflect reversal of the physiologic changes that occurred during pregnancy (see table Normal Postpartum... read more which occurs during early lactation and may last 24 to 48 hours, may be minimized by early frequent feeding. A comfortable nursing brassiere worn 24 hours/day can help, as can applying cool compresses after breastfeeding and taking a mild analgesic (eg, ibuprofen). Just before breastfeeding, mothers may have to use massage and warm compresses and express breast milk manually to allow infants to get the swollen areola into their mouth. After breastfeeding, cool compresses reduce engorgement and provide further relief. Excessive expression of milk between feedings facilitates engorgement, so expression should be done only enough to relieve discomfort.

For sore nipples, the infant’s position should be checked; sometimes the infant draws in a lip and sucks it, which irritates the nipple. The mother can ease the lip out with her thumb. After feedings, she can express a little milk, letting the milk dry on the nipples. After breastfeeding, cool compresses reduce engorgement and provide further relief.

Plugged ducts manifest as mildly tender lumps in the breasts of lactating women who have no other systemic signs of illness. Continued breastfeeding ensures adequate emptying of the breast. Warm compresses and massage of the affected area before breastfeeding may further aid emptying. Women may also alternate positions because different areas of the breast empty better depending on the infant’s position at the breast. A good nursing brassiere is helpful because regular brassieres with wire stays or constricting straps may contribute to milk stasis in a compressed area.

Mastitis Mastitis Mastitis is painful inflammation of the breast, usually accompanied by infection. Fever later in the puerperium is frequently due to mastitis. Staphylococcal species are the most common causes... read more is common and manifests as a tender, warm, swollen, wedge-shaped area of breast. It is caused by engorgement, blocking, or plugging of an area of the breast; infection may occur secondarily, most often with penicillin-resistant Staphylococcus aureus and less commonly with Streptococcus species or Escherichia coli. With infection, fever 38.5° C, chills, and flu-like aching may develop. Diagnosis of mastitis is by history and examination. Cell counts (white blood cell counts > 106/mL) and cultures of breast milk (bacteria > 103/mL) may distinguish infectious from noninfectious mastitis. If symptoms are mild and present < 24 hours, conservative management (milk removal via breastfeeding or pumping, compresses, analgesics, a supportive brassiere, and stress reduction) may be sufficient. If symptoms do not lessen in 12 to 24 hours or if the woman is acutely ill, antibiotics that are safe for breastfeeding infants and effective against S. aureus (eg, dicloxacillin, cloxacillin, or cephalexin 500 mg orally 4 times a day) should be started; duration of treatment is 7 to 14 days. Community-acquired methicillin-resistant S. aureus should be considered if cases do not respond promptly to these measures or if an abscess is present. Complications of delayed treatment are recurrence and abscess formation. Breastfeeding may continue during treatment.

Maternal anxiety, frustration, and feelings of inadequacy may result from lack of experience with breastfeeding, mechanical difficulties holding the infant and getting the infant to latch on and suck, fatigue, difficulty assessing whether nourishment is adequate, and postpartum physiologic changes. These factors and emotions are the most common reasons mothers stop breastfeeding. Early follow-up with a pediatrician or consultation with a lactation specialist is helpful and effective for preventing early breastfeeding termination.

Medications and Breastfeeding

Breastfeeding mothers should avoid taking medications if possible. When medications are necessary, the mother should avoid contraindicated medications and medications that suppress lactation (eg, bromocriptine, levodopa, trazodone). The U.S. Department of Health and Human Services maintains the extensive LactMed® database for medications and breastfeeding, which should be consulted regarding use of or exposure to specific medications or classes of drugs. For some common medications contraindicated for breastfeeding mothers, see table Some Medications Contraindicated for Breastfeeding Mothers Some Drugs Contraindicated for Breastfeeding Mothers Some Drugs Contraindicated for Breastfeeding Mothers .

When medications are necessary, the safest known option should be used; when possible, most medications should be taken immediately after breastfeeding or before the infant’s longest sleep period, although this strategy is less helpful with neonates who nurse frequently and exclusively. Knowledge of the adverse effects of most medications comes from case reports and small studies. Safety of some medications (eg, acetaminophen, ibuprofen, cephalosporins, insulin) has been determined by extensive research, but others are considered safe only because there are no case reports of adverse effects. Medications with a long history of use are generally safer than newer medications for which few data exist.



Weaning can occur whenever the mother and infant mutually desire, although preferably not until the infant is at least 12 months old. Gradual weaning over weeks or months during the time solid food is introduced is most common; some mothers and infants stop abruptly without problems, but others continue breastfeeding 1 or 2 times/day for 18 to 24 months or longer. There is no correct or easier schedule.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

  • U.S. Department of Health and Human Services: LactMed® database for drugs and breastfeeding

Drugs Mentioned In This Article

Drug Name Select Trade
Calcidol, Calciferol, D3 Vitamin, DECARA, Deltalin, Dialyvite Vitamin D, Dialyvite Vitamin D3, Drisdol, D-Vita, Enfamil D-Vi-Sol, Ergo D, Fiber with Vitamin D3 Gummies Gluten-Free, Happy Sunshine Vitamin D3, MAXIMUM D3, PureMark Naturals Vitamin D, Replesta, Replesta Children's, Super Happy SUNSHINE Vitamin D3, Thera-D 2000, Thera-D 4000, Thera-D Rapid Repletion, THERA-D SPORT, UpSpring Baby Vitamin D, UpSpring Baby Vitamin D3, YumVs, YumVs Kids ZERO, YumVs ZERO
Advil, Advil Children's, Advil Children's Fever, Advil Infants', Advil Junior Strength, Advil Migraine, Caldolor, Children's Ibuprofen, ElixSure IB, Genpril , Ibren , IBU, Midol, Midol Cramps and Body Aches, Motrin, Motrin Children's, Motrin IB, Motrin Infants', Motrin Junior Strength, Motrin Migraine Pain, PediaCare Children's Pain Reliever/Fever Reducer IB, PediaCare Infants' Pain Reliever/Fever Reducer IB, Samson-8
Biocef, Daxbia , Keflex, Keftab, Panixine
Cycloset, Parlodel
INBRIJA, Larodopa
Desyrel, Oleptro
7T Gummy ES, Acephen, Aceta, Actamin, Adult Pain Relief, Anacin Aspirin Free, Apra, Children's Acetaminophen, Children's Pain & Fever , Children's Pain Relief, Comtrex Sore Throat Relief, ED-APAP, ElixSure Fever/Pain, Feverall, Genapap, Genebs, Goody's Back & Body Pain, Infantaire, Infants' Acetaminophen, LIQUID PAIN RELIEF, Little Fevers, Little Remedies Infant Fever + Pain Reliever, Mapap, Mapap Arthritis Pain, Mapap Infants, Mapap Junior, M-PAP, Nortemp, Ofirmev, Pain & Fever , Pain and Fever , PAIN RELIEF , PAIN RELIEF Extra Strength, Panadol, PediaCare Children's Fever Reducer/Pain Reliever, PediaCare Children's Smooth Metls Fever Reducer/Pain Reliever, PediaCare Infant's Fever Reducer/Pain Reliever, Pediaphen, PHARBETOL, Plus PHARMA, Q-Pap, Q-Pap Extra Strength, Silapap, Triaminic Fever Reducer and Pain Reliever, Triaminic Infant Fever Reducer and Pain Reliever, Tylenol, Tylenol 8 Hour, Tylenol 8 Hour Arthritis Pain, Tylenol 8 Hour Muscle Aches & Pain, Tylenol Arthritis Pain, Tylenol Children's, Tylenol Children's Pain+Fever, Tylenol CrushableTablet, Tylenol Extra Strength, Tylenol Infants', Tylenol Infants Pain + Fever, Tylenol Junior Strength, Tylenol Pain + Fever, Tylenol Regular Strength, Tylenol Sore Throat, XS No Aspirin, XS Pain Reliever
Afrezza, Exubera
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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