Updated: August 2026
Breast milk provides much more than calories to a growing baby.
It contains energy, protein, fats, carbohydrates, vitamins and other nutrients needed during early life, while also providing antibodies and other biological components that support the baby's developing immune system.
The World Health Organization recommends exclusive breastfeeding for the first six months of life, followed by the introduction of safe and nutritionally adequate complementary foods while breastfeeding continues for up to two years or beyond. (World Health Organization)
But what exactly does breastfeeding do for a baby? And are common claims such as "breast milk prevents every infection" actually accurate?
Here is what parents should know.
What Is Exclusive Breastfeeding?
Exclusive breastfeeding means that a baby receives only breast milk during the first six months of life.
That means no:
Water
Pap
Infant cereal
Juice
Herbal mixtures
Other foods or drinks
Exceptions include oral rehydration solution and medically necessary drops or syrups containing vitamins, minerals or medicines. (World Health Organization)
This point is particularly important in hot climates.
A healthy exclusively breastfed baby generally does not need additional water during the first six months. Breast milk provides the fluid the baby needs. (World Health Organization)
WHO and UNICEF recommend beginning breastfeeding within the first hour after birth, exclusively breastfeeding for six months and then introducing appropriate complementary foods while breastfeeding continues. (World Health Organization)
What Are the Benefits of Breastfeeding for Babies?
1. Breast Milk Provides Nutrition for the First Six Months
Breast milk provides the energy and nutrients a healthy infant needs during the first six months of life.
It contains an appropriate combination of:
Carbohydrates
Fats
Proteins
Vitamins
Minerals
Water
Other biologically active substances
Breast milk is not identical at every feed or throughout the entire breastfeeding period. Its composition changes as lactation progresses and according to the baby's stage of development.
WHO describes breast milk as the natural first food for infants, providing the energy and nutrients required during the first months of life. (World Health Organization)
2. Colostrum Gives the Baby an Important Start
The first breast milk produced after childbirth is called colostrum.
It is usually thicker and more yellow or golden than mature breast milk and is produced in relatively small amounts.
Those small amounts are valuable.
Colostrum contains concentrated nutrients and immune components, including antibodies that help protect the newborn.
Parents should therefore not discard colostrum because it looks different from mature milk.
Early initiation of breastfeeding also helps establish feeding and stimulates continued milk production.
WHO recommends initiating breastfeeding within the first hour after birth. (World Health Organization)
3. Breastfeeding Supports the Baby's Developing Immune System
A newborn baby's immune system is still developing.
Breast milk contains antibodies and other immune-related components that contribute to protection against infection.
This does not mean a breastfed baby cannot become sick.
Breastfeeding should therefore not be described as a vaccine or as a medicine that prevents every disease.
Instead, breastfeeding provides important biological protection during a period when infants are particularly vulnerable.
4. Breastfeeding Reduces the Risk of Diarrhoeal Illness
One of the clearest benefits of breastfeeding is protection against gastrointestinal infections, including diarrhoeal disease.
WHO identifies protection against gastrointestinal infection as an important benefit of exclusive breastfeeding. (World Health Organization)
This can be particularly important in environments where unsafe water, poor sanitation or contaminated feeding equipment increase the risk of diarrhoeal illness.
Direct breastfeeding does not require water to mix feeds or bottles that may become contaminated during preparation.
However, good hygiene remains important when handling expressed breast milk or feeding equipment.
5. Breastfeeding Helps Protect Against Common Childhood Infections
WHO reports that breastfeeding protects against diarrhoea and common childhood illnesses such as pneumonia. (World Health Organization)
Breastfeeding is therefore an important child-survival intervention as well as a method of providing nutrition.
The effect should still be described accurately.
Breastfeeding reduces risk. It does not make a child immune to pneumonia, diarrhoea or every other infection.
Parents should still ensure that babies receive routine immunisation and appropriate healthcare when they become ill.
6. Breast Milk Is Well Suited to the Infant's Digestive System
Breast milk is adapted to the nutritional and physiological needs of human infants.
For most healthy babies, it provides a readily usable source of nutrients during a period when the digestive system is still developing.
This is one reason unnecessary foods and drinks are not recommended during the exclusive breastfeeding period.
Introducing foods too early can displace breast milk and may expose the infant to contaminated food or water.
At around six months, however, the situation changes.
The baby's nutritional requirements begin to exceed what breast milk alone can provide, which is why complementary feeding becomes necessary. (World Health Organization)
7. Breastfeeding Supports Healthy Growth and Development
The first two years of life represent an important period of physical and neurological development.
Adequate nutrition during this period supports:
Physical growth
Brain development
Movement and motor development
Learning
Immune development
Overall health
WHO recommends exclusive breastfeeding for six months specifically to support optimal growth, development and health. (World Health Organization)
After six months, breast milk continues to contribute important energy and nutrients while the child begins eating complementary foods.
8. Breastfeeding Is Associated With Cognitive Benefits
Breastfeeding has been associated at the population level with better performance on intelligence tests and other developmental outcomes.
WHO reports that children and adolescents who were breastfed tend to perform better on intelligence tests and have higher school attendance. (World Health Organization)
This does not mean breastfeeding determines how intelligent an individual child will become.
A child's cognitive development is influenced by many factors, including:
Genetics
Overall nutrition
Health
Education
Family environment
Responsive caregiving
Social and economic circumstances
Breastfeeding should therefore be understood as one component of healthy early development rather than a guarantee of future intelligence.
9. Breastfeeding May Reduce the Risk of Childhood Overweight and Obesity
WHO reports that children and adolescents who were breastfed as babies are less likely to experience overweight or obesity. (World Health Organization)
Again, this is a relationship at the population level.
Breastfeeding does not guarantee that a child will never become overweight.
Later diet, physical activity, genetics, sleep, family environment and many other factors influence body weight throughout childhood.
10. Breast Milk Remains Valuable After Six Months
A common misconception is that breast milk suddenly loses its nutritional value once a baby reaches six months.
It does not.
What changes is that breast milk alone is no longer sufficient to meet all of the growing child's nutritional requirements.
WHO reports that breast milk can provide half or more of a child's energy needs between 6 and 12 months and continue making a substantial nutritional contribution during the second year of life. (World Health Organization)
This is why complementary feeding means adding appropriate foods, not necessarily stopping breastfeeding.
What Should Happen at Six Months?
At around six months, infants should begin receiving nutritionally adequate and safely prepared complementary foods while breastfeeding continues.
Complementary foods are foods and drinks given in addition to breast milk when breast milk alone no longer meets all nutritional requirements.
Foods should begin in appropriate textures and quantities and become increasingly varied as the child develops.
WHO recommends responsive feeding, good food hygiene and gradually increasing the amount, variety and consistency of foods as the child grows. (World Health Organization)
Breastfeeding can continue for two years or beyond when appropriate for mother and child.
Does a Baby Need Water Before Six Months?
An exclusively breastfed baby generally does not need additional water during the first six months, even in hot weather.
Breast milk provides both food and water.
Giving additional water can reduce the amount of breast milk the baby consumes and, where water or feeding equipment is contaminated, may expose the infant to infection.
WHO specifically defines exclusive breastfeeding as giving breast milk without additional food or drinks, including water. (World Health Organization)
There may be medical situations in which a healthcare professional recommends something different, but routine water supplementation is not part of exclusive breastfeeding.
Does Breast Milk Contain Everything a Baby Needs?
Breast milk provides the nutrition needed by healthy infants during the first six months, but parents should understand an important nuance.
Some babies may require particular supplements according to national recommendations and individual circumstances.
For example, vitamin D recommendations vary according to health authority, location and individual circumstances. Current CDC guidance recommends additional vitamin D for breastfed and partially breastfed infants because breast milk alone usually does not provide enough vitamin D. (CDC)
Parents should follow advice from their child's healthcare provider and applicable national infant-feeding guidance rather than independently giving supplements.
How Can You Tell Whether a Breastfed Baby Is Getting Enough Milk?
Parents commonly worry that they cannot see exactly how much milk a breastfed baby consumes.
Useful indicators include:
Effective attachment and swallowing during feeds
Regular feeding
Appropriate urine output
Normal stools for the baby's age
Appropriate growth
The baby appearing satisfied after many feeds
Growth monitoring is particularly useful.
WHO advises parents concerned about milk intake to seek help with breastfeeding technique and attachment rather than automatically assuming that breast milk is inadequate. (World Health Organization)
Persistent poor weight gain, very few wet nappies, unusual sleepiness, difficulty feeding or signs of dehydration require medical assessment.
What If the Baby Is Sick?
Breastfeeding can be particularly valuable during illness.
Breast milk provides fluids, energy and nutrients and may be easier for some sick infants and young children to take than other foods.
WHO recommends increasing fluid intake, including more breastfeeding, during illness while continuing to offer appropriate foods according to the child's age. (World Health Organization)
However, breastfeeding is not a replacement for medical treatment.
A sick baby should be assessed when there are warning signs such as:
Difficulty breathing
Persistent vomiting
Severe diarrhoea
Poor feeding
Convulsions
Unusual drowsiness or unconsciousness
Fever in a young infant
Signs of dehydration
Significant weight loss
Breastfeeding Does Not Replace Vaccination
Breast milk contains immune components, but breastfeeding and vaccination perform different roles.
A breastfed baby should still receive all recommended childhood vaccines.
Breastfeeding does not provide reliable immunity against diseases such as:
Polio
Measles
Tetanus
Pertussis
Diphtheria
Tuberculosis
Hepatitis B
Parents should therefore follow the recommended childhood immunisation schedule.
Breastfeeding and vaccination complement each other rather than compete with one another.
Breastfeeding and Mother-Baby Bonding
Breastfeeding provides frequent opportunities for:
Skin-to-skin contact
Touch
Eye contact
Comfort
Responsive interaction
These experiences can support the relationship between a caregiver and baby.
But breastfeeding is not the only way to build a secure bond.
Babies who cannot be breastfed can still develop strong emotional relationships through responsive feeding, holding, comforting, talking, playing and consistent caregiving.
Parents should not be made to feel that a strong parent-child relationship depends exclusively on breastfeeding.
Breastfeeding and HIV
HIV requires specific consideration because the virus can be transmitted through breast milk.
However, modern antiretroviral treatment substantially reduces the risk of HIV transmission.
WHO recommends lifelong antiretroviral therapy for pregnant and breastfeeding women living with HIV and provides specific infant-feeding guidance according to national programmes and clinical circumstances. (World Health Organization)
A mother living with HIV should therefore not make infant-feeding decisions based solely on general internet advice.
She should receive counselling through HIV, antenatal, maternity and child-health services and take antiretroviral medicines exactly as prescribed.
What If Breastfeeding Is Not Possible?
Breastfeeding is strongly recommended, but there are circumstances in which a baby may not receive breast milk exclusively or at all.
These may involve:
Maternal illness
Certain medicines or treatments
Infant medical conditions
Problems with milk production
Separation of mother and baby
Other individual circumstances
Parents should not improvise unsafe substitutes.
Where breast milk is unavailable or breastfeeding is not appropriate, families should receive professional advice about safe infant feeding.
Commercial infant formula, when medically or practically required, must be prepared according to instructions using safe water and appropriate hygiene.
Homemade mixtures should not be used as substitutes for properly formulated infant feeds.
Common Breastfeeding Myths
Myth: Babies need water when the weather is hot.
Healthy babies who are exclusively breastfed generally do not need additional water during the first six months. Breast milk provides the fluid they require. (World Health Organization)
Myth: Colostrum is dirty milk and should be thrown away.
No. Colostrum is valuable early breast milk containing nutrients and immune components important to the newborn.
Myth: Breast milk becomes useless after six months.
No.
Breast milk continues providing energy and nutrients after six months. Complementary foods are introduced because the growing child now requires additional nutrition, not because breast milk suddenly loses its value. (World Health Organization)
Myth: Breastfed babies cannot get infections.
False.
Breastfeeding reduces the risk of several infections but does not provide complete protection.
Myth: Breastfeeding means a baby does not need vaccines.
False.
Breastfeeding does not replace routine childhood immunisation.
Myth: Every crying baby has insufficient breast milk.
No.
Babies cry for many reasons, including hunger, discomfort, tiredness, temperature and the need for attention.
Concerns about milk supply should be assessed using feeding technique, urine output, growth and other appropriate indicators rather than crying alone.
When Should Parents Seek Medical or Breastfeeding Support?
Seek professional help if:
The baby has difficulty attaching to the breast
Feeding is consistently difficult
The baby appears unable to suck effectively
There are very few wet nappies
The baby is not gaining weight appropriately
The baby becomes unusually weak or sleepy
There are signs of dehydration
The baby repeatedly vomits feeds
The mother has severe breast or nipple pain
The mother develops fever with a painful, red or swollen breast
You are concerned that the baby is not receiving enough milk
Early breastfeeding support can often identify problems with attachment, positioning and feeding before they become more serious.
Frequently Asked Questions
What are the main benefits of breastfeeding for babies?
Breastfeeding provides nutrition, supports immune protection, reduces the risk of gastrointestinal infections and common childhood illnesses such as pneumonia, and supports healthy growth and development. (World Health Organization)
How long should a baby be exclusively breastfed?
WHO recommends exclusive breastfeeding for the first six months of life. (World Health Organization)
Does exclusive breastfeeding include water?
No.
Exclusive breastfeeding means giving only breast milk, with limited exceptions such as medicines, vitamin or mineral drops and oral rehydration solution when needed. (World Health Organization)
When should complementary foods begin?
Appropriate complementary foods should generally begin at around six months of age while breastfeeding continues. (World Health Organization)
How long can breastfeeding continue?
WHO recommends continued breastfeeding for up to two years or beyond alongside appropriate complementary feeding. (World Health Organization)
Does breast milk protect babies from infection?
Breastfeeding provides immune protection and reduces the risk of several common infections, but it does not make a baby completely immune to disease.
Is colostrum good for newborn babies?
Yes.
Colostrum is the first breast milk and provides concentrated nutrition and important immune components.
Does breastfeeding improve brain development?
Breastfeeding supports healthy development, and population-level evidence associates breastfeeding with better cognitive outcomes. However, intelligence and development are influenced by many biological, nutritional, environmental and social factors. (World Health Organization)
Does breastfeeding replace vaccination?
No.
Breastfed children still need routine childhood immunisation.
Is breast milk still useful after the first year?
Yes.
Breast milk can continue making a meaningful nutritional contribution during the second year of life. (World Health Organization)
Key Takeaways
Breast milk provides the nutrition a healthy infant needs during the first six months of life.
WHO recommends exclusive breastfeeding for six months, meaning no additional food or drink, including water, except for limited medical exceptions. (World Health Organization)
Breastfeeding helps protect babies against diarrhoeal disease and common childhood illnesses such as pneumonia. (World Health Organization)
Breastfeeding supports healthy growth and development but does not guarantee that a child will never become ill.
Colostrum should not be discarded. It is valuable early breast milk containing nutrients and immune components.
At around six months, safe and nutritionally adequate complementary foods should be introduced while breastfeeding continues.
Breast milk remains nutritionally valuable after six months and can continue contributing significantly to a child's diet during the second year of life. (World Health Organization)
Breastfeeding does not replace vaccination, appropriate complementary feeding or medical care when a child becomes ill.
And when breastfeeding is difficult, parents should seek support rather than assuming that difficulty means breastfeeding has failed.
References and Further Reading
World Health Organization: Exclusive Breastfeeding for Optimal Growth, Development and Health
World Health Organization: Infant and Young Child Feeding
World Health Organization: Breastfeeding Questions and Answers
World Health Organization: Continued Breastfeeding for Healthy Growth and Development
World Health Organization: Appropriate Complementary Feeding
CDC: Vitamin D and Breastfeeding
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