Preventing infection and death in babies

Will breastfeeding protect my baby from infection and death?

Breastfeeding has many benefits for babies. Studies show that breast milk boosts babies’ immune system, helping fight diseases like pneumonia, bronchitis, stomach flu, and ear infections. Breastfeeding has been linked to lower rates of dangerous bowel problems, sudden infant death syndrome, cancer, and death.

A) How breastfeeding protects babies from infection

1) Breast milk components that protect the baby

Babies are born with an immune system that is relatively underdeveloped yet at the same time they are bombarded with both helpful and dangerous microbes (bacteria, viruses, fungi, and parasites) from breast milk, other foods, people, and objects. Their immune systems do not easily differentiate between the two.

In contrast, the mother's mature immune system can recognize dangerous microbes which enter her body. If the baby is infected, microbes can enter the mother's body through the breast as the baby breastfeeds. The mother's body will react by adding protective agents to her breast milk (Breakey 2015). At the same time, breast milk primes the baby to co-exist with helpful microbes.

Examples of immune components and functions of breastmilk include (Cacho 2017):

  • White blood cells that:
    • Regulate the baby’s response to infection
    • Make agents that help inactivate microbes
    • Increase in number when the baby gets sick
  • Antibodies such as:
    • IgA that keep microbes from invading the baby’s body
    • IgM and  IgG that can attack microbes
  • Bioactive molecules such as HMOs, lactoferrin, and growth factors that strengthen and regulate the baby’s immune system
  • Bacteria- and virus-destroying fats (fatty acids and monoacylglycerols) that increase in breast milk if the baby is sick (Gardner 2017; Schlievert 2019)
  • Stem cells to help repair damage from infection
  • Microbes such as bacteria, viruses, and fungi that will live in the baby’s gut and prevent disease (microbiome)

The types and amounts of these immune components vary with the mother’s genetic background, the length of the pregnancy, the amount of time since the baby’s birth, where the mother lives, her diet, and the health of the mother and her baby (Ruiz 2021). 

2) How breast milk can prime the baby's body to fight infection

The thymus is an organ found in the chest, just under the breastbone and between the lungs. It produces and helps to mature T-cells, a type of white blood cell that fights harmful microbes. It is very dynamic, growing after birth, reaching its largest size in adolescence, and then losing active cells throughout adult life. The thymus of breastfed babies is larger and produces more T-cells compared to that of infant formula-fed babies (Hossny 2020; Nabukeera-Barungi 2021).

Breastfeeding even appears to change the baby’s genes to make the immune system work better (Cacho 2017; Hartwig 2017). Small pieces of genetic material (micro RNA) may have a role in this.

B) Protection from infection

Breastfeeding has a remarkable ability to  protect babies from infection. Studies show that breastfed babies have lower rates of:

  • Pneumonia and bronchitis (Eidelman 2012; Norbäck 2018)  
  • Lung infections (Davisse-Paturet 2020; Zhou 2020)  
  • Ear infections (Eidelman 2012; van Ingen 2019) 
  • Stomach flu and diarrhea (Black 2019; Eidelman 2012; Lee 2019) 
  • Meningitis (Gartner 2005)
  • Blood infections (Gartner 2005; Liang 2018)  
  • Bladder and kidney infections (Gartner 2005; Lee 2020)  
  • Cholera (Clemens 1990; Colombara 2013) 
  • Malaria (Ogomaka 2019; van den Elsen 2020)

Numerous studies show that the longer the mother breastfeeds, the lower the risk of infection (Duijts 2010; Payne 2017). This extends to breastfeeding children after the first year of life. Protection from ear infection continues even after weaning (Frank 2019) and protection from lung infection can extend into adulthood (Wang 2020).

Preventing bacterial infections reduces the need to give antibiotics to babies (Davisse-Paturet 2019). This eliminates the cost and the risks of  side-effects of antibiotics. These side-effects may include an increased risk of (Aversa 2020; Hirsh 2017; Slykerman 2019):

  • Asthma
  • Hay fever
  • Eczema
  • Celiac disease
  • Overweight and obesity
  • Attention deficit hyperactivity disorder

These effects may be mediated by the negative effects of antibiotics on the baby’s gut microbiome (Korpela 2017; Stark 2019).

Breastfeeding protects babies from  parasites in the digestive system that can seriously harm their growth and health (Abdel-Hafeez  2013; Darby 2019; Korpe 2013).

Breastfeeding helps protect babies who are too young to be vaccinated  against infections (Curtis 2017). Breastfeeding strengthens the baby’s response to immunization and decreases the risk of fever and loss of appetite that can happen with immunization (Anderson 2019).

Because breastfed babies are less likely to develop infections, they are also less likely to be hospitalized (Christensen 2020).

C) Limiting the severity of infection

The breast monitors the baby’s health. If the baby develops an infection, the milk is adjusted to increase the number of white blood cells and other disease-fighting components to minimize its severity (Sorce 2019). This response is weaker when mothers are partially breastfeeding.

Some babies may have seizures when they have high fevers caused by infection. The risk of seizures is lower if these babies are breastfed (Mitsuda 2019; Peng 2020).

D) Protection from life-threatening illness

1) Sudden infant death syndrome

Breastfeeding reduces the risk of sudden infant death syndrome (SIDS) (Eidelman 2012; Hauck 2011; Thompson 2017).

The exact mechanism for this is not known but it is possible that breastfeeding lowers the risk of SIDS in babies by:

  • Reducing the number of infections.
  • Ensuring a healthier gut microbiome.
  • Supporting better brain development.

2) Cancer

Babies who are breastfed have been found to have a lower risk of leukemia and a type of aggressive brain cancer (neuroblastoma) (Güngör 2019; Su 2021).

3) Prevention of dangerous bowel problems

a) Twisting of the bowel

Babies can develop a condition called intussusception in which the bowel telescopes into itself. This is a very dangerous situation and the baby needs immediate medical care. Intussusception can sometimes be fixed with an X-ray procedure or the baby may require emergency surgery. Affected babies will suddenly become very upset and may vomit or have red stools.

Breastfeeding appears to decrease the risk of intussusception (Fotso Kamdem 2019; Oberle 2020; Restivo 2018).

b) Pyloric stenosis

The pylorus is a muscle that controls the rate of food leaving the stomach. If it is enlarged, food cannot leave the baby’s stomach. The baby will then vomit frequently and may be unable to grow or may lose weight. The baby can also become dehydrated. This condition is called pyloric stenosis and it usually develops between three and five weeks after birth. It is treated with surgery.

Breastfeeding appears to decrease the risk of pyloric stenosis (Mowrer 2019).

4) Prevention of Kawasaki disease

Kawasaki disease is an illness that causes inflammation in the blood vessels and can lead to serious heart disease. The cause is unknown but is thought to be a combination of genetic and environmental factors.

Exclusive breastfeeding appears to reduce the risk of this illness (Wang 2019).

E) Lower risk of death

Breastfeeding reduces the risk of infant death (Gartner 2005; Ware 2019; Zhao 2020). The reduction in the risk of death is even higher in low- and middle-income countries (Neovita  Study Group 2016). It has been estimated that the  deaths of 823,000 children each year worldwide could be prevented if every mother breastfed (Victora  2016).

No one has identified the exact reason for the higher rates of death in infant formula-fed babies. It is most likely that breastfeeding works in many ways to protect babies from disease and strengthens them to withstand and recover from it.


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