Benefits for brain and psychological development

Will breastfeeding help my baby’s brain develop?

Evidence suggests breastfeeding can benefit your baby’s brain. Studies have linked breastfeeding with higher IQ scores, better motor skills, and a lower risk of attention-deficit/hyperactivity disorder. There are also psychological benefits, as breastfeeding can calm an upset baby and reduce the pain from medical procedures. Breastfeeding helps to strengthen the bond between mother and baby, allowing optimal growth and development.

A) How the brain develops

These images show the dramatic increases in the size and complexity of a baby's brain before and after birth. (Courtesy of Dr. David van Essen, PhD, Washington University School of Medicine, St. Louis, and Dr. Terrie E. Inder, MBCHB, Brigham and Women's Hospital, Boston.)

The human brain quadruples in weight between birth and four years of age when it reaches 90% of its adult size. It is only fully mature in the mid-twenties (Dekaban 1978).

Brain cells are produced from the 6th week after conception. These cells must move into the correct position, mature, develop connections with other cells and then prune them to stabilize networks. Brain maturation is completed in early adulthood when it has about 85 billion brain cells (neurons), each connected to about 1,000 other cells, creating a network of trillions of connections (Herculano-Houzel 2009). By comparison, a cat has 300 million neurons.

As the brain develops, brain cells become coated with a greasy, white substance called myelin, allowing them to work properly. Myelin is first deposited in the brain in the second trimester and continues into a person’s 20s (Volpe 2017). Specific parts of the brain also grow until this age (Pujol 1993).

B) The benefits of breastfeeding for brain development

1) Brain function

The majority of studies of breastfeeding and long-term brain development suggest that children who breastfeed for longer than six months have better memory retention, language skills and brain function (Bar 2016; Horta 2018; Hou 2021; Ip 2007; Kramer 2008; Lenehan 2019; LeWinn 2020; Soled 2020).

Studies show that compared with infant formula-fed babies, breastfed babies have been reported to better understand words and language, analyze information, and solve problems using both language-based and non-language-based reasoning (Belfort  2013; Choi 2018; Turner 2019).

Breastfed children have been reported to have better motor skills (Grace 2017).

2) Behaviour

Breastfed babies have been shown to have a lower risk of developing attention-deficit/hyperactivity disorder and lower risk of being diagnosed with autism spectrum disorder (Bar 2016; Hof et al. 2020; San Mauro Martin 2019; Soled 2020; Tseng 2018; Tseng 2019). 

Children and adults have been shown to have fewer behavioural disorders when breastfed and benefits increased with increasing breastfeeding duration (Poton 2018; Speyer 2021). 

3) Mood

Breastfeeding appears to have long-term benefits for mood.

Breastfed babies appear to be more attuned to happy faces than those with fearful or angry expressions (Krol 2015a; Krol 2015b). Breastfeeding has been reported to reduce peer problems, neurotoicism, anxiety, and negative moods and to increase optimism and agreeableness (Turner 2019).

Being breastfed as a baby appears to decrease the risk of anxiety (Orengul 2018) and depression (Huang 2019) in older children and improve mental health in adolescence (Oddy 2010) and adulthood (Lewinsohn 1997).

C) How breastfeeding helps brain development

By breastfeeding, babies receive optimal nutrition, have a better collection of gut microbes such as bacteria, viruses, and fungi (microbiome), have fewer infections, and may experience less harmful stress. All of these can have a major role in supporting the optimum development of our complex brain and nervous system (Bull-Larsen 2019). 

1) Optimum growth of the brain tissues

Breast milk supports brain growth and development by providing ideal energy, building blocks for growth (amino acids, fatty acids, minerals), hormones, health-promoting microbes, and bioactive factors such as stem cells and microRNA

Researchers have found that when compared with infant formula-fed babies, breastfed babies have increases in brain size, in thickness of the grey and white matter of the brain, and connectivity (Bauer 2019; Ou 2016). The amount of these differences increases as the duration of breastfeeding increases (Krol 2018; Solis-Urra 2019).

In one study, babies who were exclusively breastfed for three months had better myelin coverage of brain cells than babies who were fed infant formula (Deoni 2017). The same study showed better brain performance in breastfed babies.

2) Minimizing harmful stress 

a) Decreasing the risk of infection and reducing inflammation

Breast milk prevents infection and reduces inflammation which can stress and injure the developing brain.

Breastfeeding may reduce the risk of seizures with fever (Mitsuda 2019).

b) Decreasing pain

Babies, and in particular sick or premature ones, sometimes have to undergo painful procedures. Various options have been used to decrease their pain. Breastfeeding is as good as or better than the following at decreasing pain (Graf 2020; Reece-Stremtan 2016):

  • Numbing agents 
  • Sweet-tasting solutions 
  • Giving pain medication before procedures 
  • Talking to babies
  • Holding babies
  • Swaddling 

Breast milk placed in the mouth of a premature baby can help reduce pain (Collados-Gómez 2018; Graf 2020).   Babies are especially attuned to the smell of breast milk and exposure to it can shorten crying and lower levels of stress hormones (cortisol) during painful procedures (Gellrich 2021; Zhang 2018).

c) Helping mothers respond to the baby’s needs and promoting bonding

A dyad is one thing that has two parts. This term has been used to nicely describe the relationship between mothers and babies (Vestal 1982). In some ways, a mother and her baby are like a single organism linked psychologically and  biologically. Breastfeeding supports and strengthens this bond (Peñacoba 2019; Villar 2020). When this link is weakened, babies may experience harmful stress that interferes with normal brain development and function.

Breastfeeding requires that mothers understand and respond to their babies’ hunger signs. Breastfeeding mothers appear to be more responsive to their babies and the longer the period of breastfeeding, the more responsive the mother becomes. This promotes secure emotional attachment of the baby to the mother and decreases harmful stress.   

Breast milk components change during the day and night. These variations may be providing nutrients when they are most needed by the baby, teaching and supporting the baby’s internal clock, and synchronizing the mother’s and baby’s body.

For example, breastfeeding mothers and babies have similar patterns of rises and falls in their blood levels of a particular hormone (cortisol) during the first year of life (Jonas 2018). This relationship is reduced in infant formula-feeding pairs.

3) The act of breastfeeding and the effect on the brain

The act of breastfeeding may also influence brain development.

Breastfed babies are generally in contact with more of the mother’s skin than when fed with most other feeding methods. The mother’s skin smells familiar and is always the same temperature and exposure to it can calm the baby. The mother’s skin may give the baby helpful microbes, which are known to have a role in healthy brain development. This benefit may work directly on the brain, through the promotion of beneficial hormonal pathways, or through changes in the baby’s genes (Chambers 2017; Lester 2018).


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