Breastfeeding and Breast Milk

Breastfeeding provides an infant with essential calories, vitamins, minerals, and other nutrients for optimal growth, health, and development. Breastfeeding is beneficial to both a mother and her infant and also offers an important opportunity for the pair to bond. NICHD supports many areas of breastfeeding research, including studies of the benefits of breastfeeding and breast milk, the social and cultural impacts of breastfeeding, and the nutritional components and mechanisms of disease related to breastfeeding and breast milk.

This work includes the Breastmilk Ecology: Genesis of Infant Nutrition Project. (PDF 298 KB)

About Breastfeeding and Breast Milk

Breastfeeding, also called nursing, is the process of feeding a mother's breast milk to her infant, either directly from the breast or by expressing (pumping out) the milk from the breast and bottle-feeding it to the infant. Breastfeeding and breast milk provide an infant with calories and nutrients, including macronutrients (fat, protein, and carbohydrates) and micronutrients (vitamins and minerals).1

According to the American Academy of Pediatrics (AAP) Policy Statement on Breastfeeding, women who don't have health problems should exclusively breastfeed their infants for at least the first 6 months after birth.2

The AAP suggests that, if possible, a woman should try to continue breastfeeding her infant for up to 12 months, while adding other foods, because of the benefits to both the mother and the infant.2

Although breastfeeding is the recommended method for feeding infants, and breast milk provides most of the nutrients an infant needs, it does not provide infants with adequate vitamin D.3 The current recommended daily vitamin D intake for infants and children is available on the American Academy of Pediatrics website  .


  1. Ballard, O., & Morrow, A. L. (2013). Human milk composition: Nutrients and bioactive factors. Pediatric Clinics of North America, 60(1), 49–74. Retrieved June 21, 2016, from
  2. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  3. Centers for Disease Control and Prevention. (2009, October 20). Breastfeeding: Vitamin D supplementation. Retrieved June 1, 2016, from
  4. Wagner, C. L., Greer, F. R., & American Academy of Pediatrics Section on Breastfeeding and Committee on Nutrition. (2008). Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics, 122(5), 1142–1152. Retrieved November 4, 2016, from 

What are the benefits of breastfeeding?

Research shows that breastfeeding offers many health benefits for infants and mothers, as well as potential economic and environmental benefits for communities.

Breastfeeding provides essential nutrition. Among its other known health benefits are some protection against common childhood infections and better survival during a baby's first year, including a lower risk of Sudden Infant Death Syndrome.1

Research also shows that very early skin-to-skin contact and suckling may have physical and emotional benefits.2

Other studies suggest that breastfeeding may reduce the risk for certain allergic diseases, asthma, obesity, and type 2 diabetes. It also may help improve an infant's cognitive development. However, more research is needed to confirm these findings.

For more specific information about the health benefits of breastfeeding, visit one of the following resources:


  1. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  2. Feldman-Winter, L., & Goldsmith, J. P.; Committee on Fetus and Newborn, Task Force on Sudden Infant Death Syndrome. (2016). Safe sleep and skin-to-skin care in the neonatal period for healthy term newborns. Pediatrics, 138(3), e20161889. Retrieved December 20, 2016, from 

What are the recommendations for breastfeeding?

In the United States, the American Academy of Pediatrics (AAP) currently recommends:1

  • Infants should be fed breast milk exclusively for the first 6 months after birth. Exclusive breastfeeding means that the infant does not receive any additional foods (except vitamin D) or fluids unless medically recommended.
  • After the first 6 months and until the infant is 1 year old, the AAP recommends that the mother continue breastfeeding while gradually introducing solid foods into the infant's diet.
  • After 1 year, breastfeeding can be continued if mutually desired by the mother and her infant.

The World Health Organization currently promotes as a global public health recommendation that:2

  • Infants be exclusively breastfed for the first 6 months after birth to achieve optimal growth, development, and health.
  • After the first 6 months, to meet their evolving nutritional requirements, infants should receive nutritionally adequate and safe complementary foods while breastfeeding continues for up to 2 years of age or beyond.

For the latest information on COVID-19 and breastfeeding, visit CDC at

According to the Centers for Disease Control and Prevention, the majority of new mothers start out breastfeeding, but only a minority still exclusively breastfeed by the time their infants are 6 months old. Many factors influence successful breastfeeding, including support from health care providers, family and community, and the workplace.3

The 2011 Surgeon General's Call to Action to Support Breastfeeding makes 20 recommendations to support new mothers in their decision to breastfeed.



  1. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  2. World Health Organization. (2001). The World Health Organization's infant feeding recommendation. Retrieved January 28, 2016, from 
  3. Centers for Disease Control and Prevention. (2017). U.S. Breastfeeding Rates Are Up! More Work Is Needed. Retrieved March 2, 2018, from

How do I breastfeed?

There are many mothers' groups, health organizations, and health care provider associations that provide very detailed information and support on how to breastfeed. The following overview is provided for information only—it is not meant to take the place of a health care provider or lactation consultant's advice or recommendation. Visit the Resources and Publications section to find the names of some breastfeeding organizations.

Infants who are hungry will nuzzle against their mother's breast and make sucking motions or will put their hands in their mouths. During the first weeks after birth, you may nurse your infant often, perhaps as often as eight to 12 times in 24 hours.1

After your infant is born, follow these tips for getting started:2

  • Breastfeed your infant for the first time as soon as possible after the infant is born.
  • Ask at the hospital whether an on-site lactation consultant is available to assist you.
  • Request that the hospital staff not feed your infant any other foods or formula unless it is medically necessary.
  • Allow your infant to stay with you throughout the day and night at the hospital so that you can breastfeed often. If this is not possible, ask the nurses to bring your infant to you each time for breastfeeding.
  • Avoid giving your infant pacifiers or artificial nipples so that the infant gets used to latching on to just your breast.

Infants will naturally move their head while looking and feeling for a breast to feed. There are many ways to start feeding your infant, and the best approach is the one that works for you and your infant. The steps below can help with getting your infant to "latch" on to the breast for feeding.2

  • Hold your infant against your bare chest. Dress your infant in only a diaper to ensure skin-to-skin contact.
  • Keep your infant upright, with his or her head directly under your chin.
  • Support your infant's neck and shoulders with one hand and his or her hips with your other hand. Your infant may try to move around to find your breast.
  • Your infant's head should be slightly tilted back to make nursing and swallowing easier. When his or her head is tilted back and the mouth is open, the tongue will naturally be down in the mouth to allow the breast to go on top of it.
  • At first, allow your breast to hang naturally. Your infant may open his or her mouth when your nipple is near his or her mouth. You also can gently guide the infant to latch on to your nipple.
  • While your infant is feeding, his or her nostrils may flare to breathe in air. Do not panic—this flaring is normal. Your infant can breathe normally while breastfeeding.
  • As your infant tilts backward, support his or her upper back and shoulders with the palm of your hand and gently pull your infant close.

A good latch is important for both effective breastfeeding and your own comfort. Review the following signs to determine whether your infant has a good latch:2

  • The latch feels comfortable and does not hurt or pinch. How it feels is a more important sign of a good latch than how it looks.
  • Your infant does not need to turn his or her head while feeding. His or her chest is close to your body.
  • You see little or no areola (pronounced uh-REE-uh-luh), which is the dark-colored skin on the breast that surrounds the nipple. Depending on the size of your areola and the size of your infant's mouth, you may see a small amount of areola. If more areola is showing, it should seem that more is above your infant's lip and less is below.
  • Your infant's mouth will be filled with breast when in the best latch position.
  • Your infant's tongue is cupped under the breast, although you might not see it.
  • You can hear or see your infant swallowing. Because some babies swallow so quietly, the only way of knowing that they are swallowing is when you hear or see a pause in their breathing.
  • Your infant's ears "wiggle" slightly.
  • Your infant's lips turn outward, similar to fish lips, not inward. You may not even see your infant's bottom lip.
  • Your infant's chin touches your breast.

To break the suction and end a breastfeeding session, insert a clean finger between your breast and your infant's gums. After you hear a soft pop, pull your nipple out of your infant's mouth.1

You should allow your infant to set his or her own nursing pattern. Many newborns will feed for 10 to 15 minutes on each breast. If your infant wants to nurse for a much longer period—say 30 minutes or longer on each breast—he or she may not be getting enough milk.1

For more information, visit the Office on Women's Health's page on learning how to breastfeed your infant.


  1. American College of Obstetricians and Gynecologists. (2016, March). Breastfeeding your baby. Retrieved June 1, 2016, from 
  2. U.S. Department of Health and Human Services Office on Women's Health. (2010, August). Breastfeeding: Learning to breastfeed. Retrieved January 28, 2016, from

What is weaning and how do I do it?

Weaning is the process of switching an infant's diet from breast milk or formula to other foods and fluids. In most cases, choosing when to wean is a personal decision. It might be influenced by a return to work, the mother's or infant's health, or just a feeling that the time is right.1

Weaning an infant is a gradual process. The American Academy of Pediatrics (AAP) recommends feeding infants only breast milk for the first 6 months after birth. After 6 months, the AAP recommends a combination of solid foods and breast milk until the infant is at least 1 year old.2 The Academy advises against giving cow's milk to children younger than 1 year old.3

You may have difficulty determining how much to feed your child and when to start introducing solid foods. The general guidance below, as reported by the National Library of Medicine, demonstrates the process of weaning for infants up to 6 months of age.4 You should speak with your infant's health care provider before attempting to wean your infant to make sure that he or she is ready for weaning and for complete guidance on weaning.

  • Birth to 4 months of age
    • During the first 4 to 6 months, infants need only breast milk or formula to meet their nutritional needs.
      • If breastfeeding, a newborn may need to nurse eight to 12 times per day. By 4 months of age, an infant may need to nurse only four to six times per day.
      • By comparison, formula-fed infants may need to be fed about six to eight times per day, with newborns consuming about 2 to 3 ounces per feeding. The number of feedings will decrease as the infant gets older, similar to breastfeeding.
  • 4 to 6 months of age
    • At 4 to 6 months of age, an infant needs to consume 28 to 45 ounces of breast milk or formula per day and often is ready to start being introduced to solid food.
    • Starting solid foods too soon can be hazardous, so an infant should not be fed solid food until he or she is physically ready.
    • Start solid feedings (1 or 2 tablespoons) of iron-fortified infant rice cereal mixed with breast milk or formula, stirred to a thin consistency.
    • Once the infant is eating rice cereal regularly, you may introduce other iron-fortified instant cereals.
    • Only introduce one new cereal per week so that intolerance or possible allergies can be monitored.

For more information on weaning your infant, visit MedLinePlus: Feeding Patterns and Diet—Children 6 Months to 2 Years.


  1. KidsHealth from Nemours. (2014). Weaning your child. Retrieved June 27, 2016, from 
  2. American Academy of Pediatrics (AAP). (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  3. AAP. (2015). Ages & stages: Why formula instead of cow's milk? Retrieved January 28, 2016, from 
  4. MedlinePlus. (2016). Feeding patterns and diet—babies and infants. Retrieved June 1, 2016, from

When breastfeeding, how many calories should moms and babies consume?

Mother breastfeeding baby; text on top: how many calories do you need when breastfeeding?

Many new mothers wonder if they need to consume more calories (also called energy) during breastfeeding, but the answer is no. You can take in the same number of calories that you did before becoming pregnant. This strategy helps with weight loss after birth.1

The Dietary Guidelines for Americans (DGAs) for caloric intake for all women 19 to 50 years old are based on activity level, as follows:2

  • Sedentary: 1,800 to 2,000 calories per day
  • Moderately active: 2,000 to 2,200 calories per day
  • Active: 2,200 to 2,400 calories per day

The increased caloric need for women who are breastfeeding is about 450 to 500 calories per day.3 Women who are not trying to lose weight following pregnancy should supplement the above DGA calories per day by 450 to 500 calories. Often an increase in a normally balanced and varied diet is enough to meet your body's needs. Whether or not to increase caloric intake during breastfeeding is a decision that should be made with the assistance of a health care provider.

Poorly nourished mothers, those on vegan diets or other special diets, and those with certain health conditions may require a supplement of docosahexaenoic acid (DHA) in addition to multivitamins to ensure complete nutrition for breastfeeding.4

Women who are breastfeeding may have additional requirements for vitamins and minerals. Learn more about your specific nutritional needs during breastfeeding at

Women also can use the U.S. Department of Agriculture's (USDA's) My Plate Daily Checklist for Moms to develop a personalized food plan based on their activity level, amount of breastfeeding, age, and other characteristics.

The estimated energy requirements (in calories per day) for infants are based on their age, size, and sex. Estimated energy requirements developed by the USDA are as follows:5


  • 1 to 3 months: 472 to 572 calories per day
  • 4 to 6 months: 548 to 645 calories per day
  • 7 to 9 months: 668 to 746 calories per day
  • 10 to 12 months: 793 to 844 calories per day


  • 1 to 3 months: 438 to 521 calories per day
  • 4 to 6 months: 508 to 593 calories per day
  • 7 to 9 months: 608 to 678 calories per day
  • 10 to 12 months: 717 to 768 calories per day

The above daily calorie ranges are for infants of a specific weight and length. The USDA has information on how to find out the daily calorie needs of your infant based on his or her size (PDF - 34 MB). 

The USDA also has determined the daily protein, carbohydrate, and fat requirements for infants (PDF 34 MB).

Visit the Office on Women's Health's Breastfeeding page to learn what signs to watch for to determine whether your baby is getting enough breast milk.

The DGAs for infants increase as the infants get older. By the time that children are 2 to 3 years of age, daily calorie needs are 1,000 to 1,400 calories per day, depending on the child's activity level. For children who are older, see the 2015–2020 DGAs.


  1. U.S. Department of Health and Human Services Office on Women's Health. (2014).Your guide to breastfeeding. Retrieved June 1, 2016, from (PDF 2.2 MB)
  2. U.S. Department of Agriculture (USDA) & U.S. Department of Health and Human Services. (2015). 2015–2020 Dietary Guidelines for Americans (8th ed.). Retrieved January 28, 2016, from
  3. American College of Obstetricians and Gynecologists. (2016). Breastfeeding your baby. Retrieved June 1, 2016, from 
  4. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  5. USDA. (2009). Nutritional needs for infants. In Infant Nutrition and Feeding: A Guide for Use in the WIC and FSF Programs (11–40). Retrieved October 13, 2016, from (PDF 3.4 MB)

Are there any special conditions or situations in which I should not breastfeed?

In special cases, women may be advised not to breastfeed. These instances include when a woman is taking certain medications or drugs, when she has been diagnosed with a specific illness, or when other specific conditions apply.

For the latest information on COVID-19 and breastfeeding, visit CDC at

Certain medications are known to be dangerous to infants and can be passed to your infant in your breast milk. Women taking the following medicines should speak with their health care providers before considering breastfeeding:

  • Antiretroviral medications (for HIV/AIDS treatment)1
  • Birth-control medications containing estrogen, until breastfeeding has been well established2
  • Cancer chemotherapy agents1
  • Illegal drugs1
  • Certain medications prescribed to treat migraines, such as ergot alkaloids3
  • Mood stabilizers, such as lithium and lamotrigine4
  • Sleep-aid medicines5

In addition, women who are undergoing radiation therapy should not breastfeed, although some therapies may require only a brief interruption of breastfeeding.1

The above list of medications and other drugs is only a guideline. Before breastfeeding, you should speak with your health care provider about all medications that you are taking.5 These include prescribed medications, over-the-counter medicines, vitamins, and herbal therapies.

Medications that are safe during pregnancy may also be safe for you to continue while you are breastfeeding, although you should check with your health care provider to make sure they are safe before you breastfeed.5

Contact your infant's health care provider if you see any signs of a reaction to your breast milk in your infant, such as diarrhea, excessive crying, or sleepiness.5

Women with certain illnesses and infections may be advised not to breastfeed because of the danger of passing the illness or infection to the breastfed infant.

If you have any of the following conditions, breastfeeding your infant is NOT advised. For more information, speak with your health care provider:1

  • Infection with HIV
  • Infection with human T-cell lymphotropic virus type I or type II
  • Untreated, active tuberculosis

If you are sick with the flu, including the H1N1 flu (also called the swine flu), you should not stop feeding your infant expressed milk. You should avoid being near your infant, however, so that you do not infect him or her. To avoid infecting your infant, someone who is not sick should give your infant your expressed milk.6

For more information on the flu, including the H1N1 flu, visit the following Centers for Disease Control and Prevention (CDC) webpage:

If you have Zika virus or live in areas where Zika virus is found, the CDC recommends you continue to breastfeed your infant. Although Zika virus has been detected in breast milk, there are no reports of transmission of the virus through breastfeeding, and the benefits of breastfeeding are thought to outweigh the risks.7  NICHD is partnering with other NIH Institutes and the Brazilian research organization Fundação Oswaldo Cruz (Fiocruz) to study Zika virus transmission in 10,000 pregnant women and their infants. If possible, breast milk will be collected from the mothers. For more information on breastfeeding and Zika virus, visit the CDC's page on Zika virus transmission and its Q&A for health care providers.

In the United States, the American Academy of Pediatrics and the CDC recommend against breastfeeding if you are HIV positive; the same advice applies in other developed countries.1,8 Without any specific interventions to reduce transmission, infants breastfed by HIV-positive mothers have an increased chance of acquiring HIV through the breast milk. This rate increases if infants are breastfed longer and for mothers with newly-acquired HIV.9

Only HIV-positive mothers living in developing countries should consider breastfeeding their babies, especially if a safe and reliable source of infant formula is unavailable.9 This is because breast milk may protect against malnutrition and diarrhea, which are major causes of infant mortality in some areas of the developing world. If an HIV-positive woman decides to breastfeed her baby, research indicates that the risk of transmitting HIV to her baby is reduced if she exclusively breastfeeds (does not use a combination of formula and breast milk) and if she and her infant take antiretroviral drugs.10,11

In some additional situations, or if women or infants have certain health conditions, women may be advised not to breastfeed or may have difficulty breastfeeding.

  • Women with certain chronic illnesses may be advised not to breastfeed, or will be advised to take steps to ensure their own health while breastfeeding. For example, women who have diabetes should monitor their blood sugar levels regularly, may need to reduce their insulin, and may need a snack containing carbohydrates before or during breastfeeding.12 Also, women who are underweight, including those with thyroid conditions or certain bowel diseases, may need to increase their calories to maintain their own health during breastfeeding.
  • Women who have had breast surgery in the past may face some difficulties with breastfeeding.13
  • Women who actively use drugs or do not control their alcohol intake, or who have a history of these situations, also may be advised not to breastfeed.14
  • Infants who have galactosemia—a rare metabolic disorder in which the body cannot digest the sugar galactose—should not be breastfed. Galactosemia is detected by newborn screening, allowing proper treatment and diet to begin immediately. If not detected, the galactose builds up and becomes toxic for the infant, leading to liver problems, intellectual and developmental disabilities, and shock.5


  1. Centers for Disease Control and Prevention (CDC). (2015). Breastfeeding: Diseases and conditions. Retrieved March 21, 2016, from
  2. American College of Obstetricians and Gynecologists. (2016). Breastfeeding your baby. Retrieved June 1, 2016, from 
  3. Tepper, D. (2015). Pregnancy and lactation—migraine management. Headache: The Journal of Head and Face Pain, 55, 607–608. Retrieved January 28, 2016, from  (PDF 209 KB)
  4. Massachusetts General Hospital Center for Women's Mental Health. (2015). Breastfeeding & psychiatric medications. Retrieved January 29, 2016, from 
  5. March of Dimes. (2016). Keeping breast milk safe and healthy. Retrieved June 2, 2016, from 
  6. CDC. (2009, October 23). 2009 H1N1 (swine flu) and feeding your baby: What parents should know. Retrieved April 27, 2012, from
  7. Dupont-Rouzeyrol, M., Biron, A., O'Connor, O., Huguon, E., & Descloux, E. (2016). Infectious Zika viral particles in breastmilk. Lancet, 387(10023), 1051.
  8. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved March 11, 2016 from 
  9. World Health Organization (WHO). (2008). HIV transmission through breastfeeding: A review of the available evidence. Retrieved March 11, 2016, from  (PDF - 835 KB)
  10. WHO. (2010). Guidelines on HIV and infant feeding. Retrieved March 11, 2016, from  (PDF 1.58 MB)
  11. Coovadia, H. M., Rollins, N. C., Bland, R. M., Little, K., Coutsoudis, A., Bennish, M. L., & Newell, M.-L. (2007). Mother-to-child transmission of HIV-1 infection during exclusive breastfeeding in the first 6 months of life: An intervention cohort study. Lancet, 369(9567), 1107–1116. Retrieved March 11, 2016, from 
  12. American Diabetes Association. (2007). Nutrition recommendations and interventions for diabetes. A position statement of the American Diabetes Association. Diabetes Care, 30(Suppl 1), S48–S65. Retrieved January 29, 2016, from 
  13. BFAR. (2009). General frequently asked questions (FAQ) about breastfeeding after breast and nipple surgeries. Retrieved January 29, 2016, from 
  14. National Institute on Drug Abuse. (2015). Substance use while pregnant and breastfeeding. Retrieved January 29, 2016, from


How do I pump and store breast milk?

There are many mothers' groups, health organizations, and health care provider associations that provide very detailed information and support on how to pump breast milk. The following overview is provided for information only—it is not meant to take the place of a health care provider or lactation consultant's advice or recommendation. Visit the Resources and Publications section to find organizations that provide information on pumping breast milk.

If you are unable to breastfeed your infant directly, it is important to remove milk during the times that you would normally feed your infant. Removing milk from your breasts is called expressing the milk. Expressing milk will help you to continue making milk.

Before expressing breast milk, wash your hands thoroughly. Only express milk when you are in a clean area. You do not need to wash your breasts or nipples before expressing milk. If you need help to get your milk flowing, placing an item of your infant's near to you often works.

There are three methods for expressing your breast milk:1

  • Hand expression: For hand expression, you use your hand to manually massage and compress your breast to remove milk. 
  • Manual pump: To operate a manual pump, you use your hand and wrist to operate a hand-held pumping device that removes milk from your breast. 
  • Electric breast pump: An electric breast pump runs on a battery or through an outlet plug. It can pump milk from one breast or from both breasts at the same time.

For more information on pumping breast milk, visit the Office on Women's Health page on pumping and breast milk storage.

Breast milk can be stored in clean glass bottles or hard, BPA-free plastic bottles with tight-fitting lids. After pumping, refrigerate or freeze milk immediately. You should store milk in small batches (2 to 4 ounces), depending on the amount that you normally feed your infant at one time.1,2

For refrigeration, storage for as long as 5 to 8 days is acceptable only for very clean expressed milk. If freezing, store the milk in small (2-ounce to 4-ounce) batches. Frozen milk is good for 3 to 6 months. After thawing, use milk within 24 hours and do not refreeze it because of the risk of contamination.1,3

For more information on pumping and storing breast milk, including recommended storage temperatures, visit these pages:


  1. U.S. Department of Health and Human Services Office on Women's Health. (2015). Breastfeeding: Pumping and milk storage. Retrieved January 29, 2016, from
  2. American Academy of Pediatrics. (n.d.). Breastfeeding initiatives: FAQs. Retrieved April 27, 2012, from 
  3. Centers for Disease Control and Prevention. (2010). Breastfeeding: Proper handling and storage of human milk. Retrieved April 27, 2012, from

Do breastfed infants need other nutrition?

Although breastfeeding is the recommended method for feeding infants and breast milk provides most of the nutrients an infant needs, it does not provide infants with adequate vitamin D. Vitamin D is required to prevent rickets, a type of vitamin D deficiency. This disease is rare among breastfed infants but can occur if vitamin supplementation or exposure to sunlight is inadequate. (Exposure to sunlight helps the body to make vitamin D in place of supplementation.)1

The current American Academy of Pediatrics (AAP)–recommended daily vitamin D intake is 400 IU per day for all infants and children beginning from the first few days after birth.2 Human breast milk contains a vitamin D concentration of 25 IU per liter (about 4 cups) or less. Therefore, to meet the 400 IU daily requirement, supplementation is required.

If an infant is weaned to a vitamin D-fortified infant formula and consumes at least 4 cups per day, then additional supplementation with vitamin D is not necessary.1

Breastfeeding is supplemented by feeding an infant expressed breast milk from a bottle, formula, or breast milk from another mother. Such supplementation may be needed in the following situations:3

In the Mother:

  • Breast surgery or other trauma
  • Primary breast insufficiency that prevents adequate milk production
  • Physical separation from the infant
  • Serious illness

In the Infant:

  • Weight gain insufficient to maintain health (also sometimes called failure to thrive)
  • Cleft lip and/or palate or other abnormality that prevents normal suckling ability
  • Jaundice or liver problems
  • Serious illness or prematurity that requires the infant to be cared for in a special nursery

Many of these conditions require a health care provider's care. You should always talk with your child's health care provider about whether to supplement your breastfeeding.

To keep supplementation from shortening or otherwise interfering with breastfeeding, you should supplement only after your infant is breastfeeding effectively and thriving on your breast milk.3

Mixing formula with breast milk in the same container is one way of supplementing breast milk. You may want to supplement your breast milk with infant formula if your milk supply is low or when you are physically separated from your infant.3

Supplementing your breast milk with formula, however, may not be nutritionally the same as giving breast milk.4 Discuss the practice with your infant's health care provider before starting to mix formula with your breast milk.

The term "complementary feeding" refers to giving your baby solid and liquid foods other than breast milk or infant formula. As babies grow, they have nutritional needs that breast milk or infant formula alone cannot meet. Complementary feeding helps meet those nutritional needs. It is also important for infants' jaw and muscle development and helps them develop speech later.5

The AAP and the World Health Organization (WHO) recommend introducing safe, nutritious complementary foods into your infant's diet around 6 months of age.4,6 The exact timing depends on the infant's developmental readiness, meaning whether the baby can open his or her mouth and lean forward when interested in food. Studies show that introducing complementary foods before 4 months offers little health benefit to the infant and can increase the risk of food allergies and choking.5

Some complementary foods are often called "baby foods" and can be pureed or mashed-up versions of meats, fruits, and vegetables. Different foods offer different nutrients. For example, around 4 to 6 months of age, babies' iron and zinc needs are higher than what breast milk or infant formula alone can provide. Complementary feeding of fortified cereals or pureed meats can provide these nutrients.

If you have any questions about complementary feeding, or if your family has a history of food allergies, talk to your infant's health care provider.


  1. Centers for Disease Control and Prevention. (2015). Vitamin D supplementation. Retrieved January 29, 2016, from
  2. Wagner, C. L., Greer, F. R., & American Academy of Pediatrics Section on Breastfeeding and Committee on Nutrition. (2008). Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics, 122(5), 1142–1152. Retrieved November 4, 2016, from 
  3. Kellams, A., et al. (2017). Academy of Breastfeeding Medicine, Clinical Protocol #3: Supplementary Feedings in the Healthy Term Breastfed Neonate. Breastfeeding Medicine, 12(3): 1-11. Retrieved from May 12, 2020.   (PDF 380 KB)
  4. American Academy of Pediatrics. (2012). Breastfeeding and the use of human milk. Pediatrics, 129(3), e827–e841. Retrieved April 27, 2012, from 
  5. U.S. Department of Agriculture Food and Nutrition Service. (2009). Infant Nutrition and Feeding: A Guide for Use in the WIC and CSF Programs. Retrieved October 13, 2016, from (PDF 3.4 MB)
  6. World Health Organization. (n.d.) Complementary feeding. Retrieved October 12, 2016, from 

NICHD Breastfeeding and Breast Milk Research Goals

NICHD seeks to understand the aspects of breastfeeding and breast milk that lead to optimal health for mothers and infants and optimal development for infants. To meet its goals, NICHD supports and conducts research that addresses breastfeeding practices and initiatives throughout the nation and abroad.

Learn more about the need for human milk research. (PDF 298 KB)

Some of the projects related to breastfeeding and breast milk include (but are not limited to):

  • Understanding the full range of benefits from breastfeeding and breast milk for mother and infant and their short-, medium-, and long-term influences on health and disease
  • Examining the social, cultural, and economic impacts of breastfeeding in the U.S. and worldwide, as well as the factors that positively and negatively influence breastfeeding decisions
  • Elucidating the nutritional and biochemical components of breast milk and how they might prevent, treat, or reduce the severity of various diseases
  • Identifying nutritional and other components of breast milk that might be lacking and creating and evaluating strategies to ensure that infants receive these components in various settings
  • Understanding the effects of diseases such as malaria, and of chronic conditions such as HIV/AIDS, on breast milk, breastfeeding practices, and treatments for diseases
  • Collaborating with agencies and organizations to raise awareness of the scientific evidence that underlies breastfeeding recommendations

The Institute also supports efforts to meet the public health goals outlined by the U.S. Department of Health and Human Services (HHS) Healthy People 2020 initiative, such as increasing the number of infants who are breastfed, through various awareness and outreach efforts. For more information on the Healthy People 2020 goals for breastfeeding, visit

Breastfeeding and Breast Milk Research Activities and Advances

Several NICHD organizational units (OUs) support and conduct research on breastfeeding and breast milk. Many of these efforts overlap and require trans-NICHD and trans-NIH collaboration. The following is only a summary of some of these efforts.

Pediatric Growth and Nutrition Branch (PGNB) research on breastfeeding is part of a larger research program on nutrition that uses a systems approach to incorporate biological, environmental, and other critical components as integral to public health. This program also explores nutritional variables, including those specific to breastfeeding, in both domestic and international contexts. Some of the PGNB projects related to breastfeeding include:

PGNB Study Results: Longer Breastfeeding Does Not Protect Against Childhood Obesity

An increasing number of children worldwide are overweight or obese. Overweight and obese children are at a higher risk for a range of medical problems, including type 2 diabetes. Previous studies have indicated that children who were breastfed were less likely to become obese in early life, compared with children who were fed with infant formula. But these studies were observational, making it hard to rule out other causal effects. To better investigate a possible link between breastfeeding and obesity, researchers followed up on a large clinical trial in Belarus that tested whether an intervention promoted breastfeeding in infants. Women who received the intervention breastfed their infants longer and more exclusively than women in the control group. The researchers went back to 13,800 of these infants when they were 11.5 years of age. Children who were breastfed longer or more exclusively were just as likely to be obese or overweight as children from the control group. The children also had similar levels of insulin-like growth factor, which regulates childhood growth. The researchers concluded that although breastfeeding has many other advantages, it is unlikely to curb increasing rates of obesity. (PMID: 23483175)

  • Improving knowledge of maternal-fetal and newborn nutrition, particularly for preterm infants, low-birth-weight (LBW) infants, and infants in resource-poor areas;
  • Elucidating the nutritional and bioactive components of breast milk, such as iron, and how these influence the duration of exclusive breastfeeding and the timing of introduction of supplemental or complementary foods;
  • Understanding the role of breast milk and its components in gastrointestinal immunity, prevention of respiratory disease, and prevention and treatment of infections and inflammation;
  • Identifying biomarkers for exposure, status, and function of vitamin D, zinc, and other nutrients and micronutrients and defining the long-term impacts of nutritional deficiency during infancy;
  • Exploring the nutritional needs of women with HIV/AIDS and how best to safely wean their infants to minimize exposure to the disease while still providing optimal nutrition, especially in resource-poor areas; and
  • Contributing scientific expertise to the World Health Organization (WHO), the United Nations World Food Programme, the President's Emergency Plan for AIDS Relief (PEPFAR), the NIH Office of AIDS Research, and other groups' guidelines and best practice recommendations on infant feeding and nutrition.

The Institute's Pregnancy and Perinatology Branch (PPB) supports basic and clinical studies aimed at understanding the etiology, pathophysiology, therapy, and follow-up of health during the perinatal and neonatal periods, as well as research on in utero conditions and their influence on health outcomes. Among the PPB's projects within this context related to breastfeeding are:

PPB Study Results: Depression During Pregnancy May Affect the Nutritional Quality of Breast Milk

Many women experience depression during pregnancy and in the early months after childbirth. Previous studies showed a link between docosahexaenoic acid (DHA) and positive mental health. DHA is also known to be important for optimal brain development in the growing fetus and in infants. Based on these earlier findings, researchers conducted a study to examine whether symptoms of depression during pregnancy affect the concentration of DHA in breast milk. Researchers conducted a survey of 287 women to assess whether they experienced depressive symptoms. Breast milk samples were collected from the same women 4 months after childbirth to measure the concentration of DHA. The results from the study showed that women who reported depressive symptoms in the first 20 weeks of pregnancy had lower concentrations of DHA in their breast milk. The same association was not found in women who reported depressive symptoms later in pregnancy. Because depression prior to pregnancy was not measured, it was unclear whether the women in this study were experiencing chronic depression or temporary depression due to stress or hormonal changes associated with pregnancy. However, because levels of DHA measured in breast milk are reflective of long-term influences on the body to store DHA over time, low levels of DHA in breast milk are likely associated with chronic depression. (PMID: 22223516)

PPB Podcast: Lactation consultants increase breastfeeding rate

In an NICHD Research Developments podcast, Dr. Karen Bonuck, professor of women's health and family and social medicine at the Albert Einstein College of Medicine, discusses her research on interventions to increase breastfeeding in low-income and multi-ethnic women. Her study, supported by NICHD and published in the American Journal of Public Health, found that women who were visited by lactation consultants were three times more likely to breastfeed for 3 months compared to women who received usual care. The key, explains Dr. Bonuck, is integrating the lactation consultants into women's routine primary care. Lactation consultants approached women while they were waiting to attend prenatal visits and later visited women in their homes. (PMID: 24354834)

PPB Study Results: What Predicts Intent to Breastfeed Exclusively?

All major medical organizations endorse exclusive breastfeeding for the first 6 months after birth. However, only 13.3% of infants in the United States are exclusively breastfed through 6 months, with major differences in rates by maternal race, ethnicity, education, and income. Women who, while pregnant, form an intention to breastfeed their baby are most likely to do so. Scientists measured the association between intentions to exclusively breastfeed and knowledge of infant health benefits, feeding guidelines, and comfort related to breastfeeding in social settings. The study was conducted with a group of lower-income, ethnically diverse urban women. The results showed that 46% of women in the study intended exclusive breastfeeding, an equal proportion (46%) intended to use mixed feeding, and 8% intended to use formula feeding exclusively. Maternal knowledge about infant health benefits, as well as comfort with breastfeeding in social settings, was directly related to intention to exclusively breastfeed, and to breastfeed exclusively for longer periods of time. (PMID: 21342016)

Scientists analyzed data from 1,636 women who were part of the Community Child Health Network, an NICHD-sponsored project. They found that Spanish-speaking Hispanic mothers were the most likely to initiate breastfeeding, followed by English-speaking Hispanic mothers and white mothers. Black mothers are the least likely to initiate and maintain breastfeeding. In all ethnic groups, feeding with formula in the hospital led to a shorter time spent breastfeeding. These factors must be considered when trying to reduce racial and ethnic disparities in breastfeeding. (PMID: 27405771)

  • Studies on the optimal timing of breastfeeding initiation, especially in resource-poor countries, and the effects on infant health outcomes, including infant mortality;
  • Research on the effects of breastfeeding on brain development, specifically development of the medullary raphe of the brainstem and the serotonin systems, and its mechanisms for reducing the risk for Sudden Infant Death Syndrome;
  • Investigations of how breast milk improves neurodevelopmental and other outcomes for neonates, including extremely LBW (ELBW) infants and preterm infants; and
  • Research on breast milk and its effects on severity of and treatment for certain newborn diseases, such as necrotizing enterocolitis, retinopathy of prematurity, and jaundice.

The Maternal and Pediatric Infectious Disease Branch conducts and supports research on breast milk and breastfeeding within the context of HIV/AIDS infection and transmission. This research includes not only studies of the prevention of mother-to-child transmission (MTCT) of HIV/AIDS through a combination of limited duration of breastfeeding and medication interventions, but also the biological mechanisms by which MTCT occurs via breast milk. Additional studies examine the conditions that enhance or reduce the chance of transmission through breast milk, such as viral load and the number of mammary cells infected with HIV. Branch studies also aim to provide evidence about the best practices for breastfeeding, formula feeding, weaning, and supplementation for populations affected by HIV/AIDS. This research is conducted both domestically and abroad and includes partnerships and collaborations with other NIH Institutes and Offices, the WHO, PEPFAR, and other agencies and organizations in the United States and elsewhere.

The NICHD Population Dynamics Branch supports research on breastfeeding within the context of its social and societal impacts. Some of these studies aim to understand the home and socioeconomic factors that influence breastfeeding decisions, while other efforts aim to quantify the effects of workplace and public policies on breastfeeding and breastfeeding duration. This work also examines the potential impact of breastfeeding on current and future health and productivity in population representative samples.

Researchers in the NICHD Division of Intramural Population Health Research also conduct research on breastfeeding and breast milk. These studies include (but are not limited to) the effects of maternal nutrition and malnutrition on breast milk composition and subsequent effects on fetal and infant nutrition. Additional research examines the factors that influence breastfeeding decisions, particularly among those in at-risk groups, including African American mothers who live in low-income areas, as well as the long-term effects of breastfeeding on chronic diseases, such as obesity.

Through its Obstetric and Pediatric Pharmacology and Therapeutics Branch (OPPTB), NICHD also studies the effects of certain drugs on pregnancy and neonatal outcomes. Among the studies supported by the OPPTB are those that examine whether certain medications are transmitted via breast milk and their effects on infant development.

As explained above, NICHD OUs collaborate with each other, with NIH Institutes and Centers, and with other governmental and non-governmental organizations in the United States and worldwide. Some of these partnership and activities are described below.

  • The NICHD PPB collaborated with the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration to conduct the Infant Feeding Practices II Survey aimed at examining infant feeding practices, including breastfeeding, among a large cohort of women and the impacts of these practices on infant health. 
  • The Neonatal Research Network (NRN), supported through the PPB, investigates the safety and efficacy of treatment and management strategies for newborn infants. The NRN has led several of the PPB's efforts on breastfeeding and neurodevelopmental outcomes for ELBW infants and on nutritional management of preterm, LBW, and ELBW infants.

NICHD also participated in activities related to the Surgeon General's Call to Action to Support Breastfeeding.

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