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Breastfeeding and Mental Health

There is a body of research which examines the relationship between postpartum breastfeeding and mental health. Significant results linking breastfeeding and the mental health of mothers and their children¹ suggest that whilst breastfeeding provides an important source of nutrition for the child², it is “not simply a meal at the breast” ³. Rather, it is an important event where reciprocal “physical, biochemical, hormonal, and psychosocial exchange” occurs between the mother and child.³

Research reveals links between breastfeeding and the mother’s mood, stress levels and postpartum depression.  Scientific evidence also suggests breastfeeding may affect the child’s social and emotional development and links between breastfed children and the development of Autism Spectrum Disorder (ASD) have been examined. Furthermore, the underlying physiological mechanisms of these relationships have been proposed. Breastfeeding is also noted to improve the quality of bonding within mother-infant dyads.

Nature of Relationship Between Breastfeeding and Mental Health

It should be noted that the exact nature of the relationships between breastfeeding and mental health of the mother and/or child is unclear to scientists.

This is due to several reasons, including the variability of how breastfeeding and its effects are measured across studies.¹ Furthermore, there are complex interactions between numerous psychological, sociocultural and biochemical factors which are not yet fully understood⁴. There are also studies which present conflicting or opposing results which further obscure the exact nature of the relationships.⁴

Scientists also emphasise the need to distinguish correlation and causation relationships between breastfeeding and the mental health of mothers and/or their children.¹ Additionally, whether the relationship between breastfeeding and aspects of mental health are unidirectional (i.e. one causes the other) or bidirectional (i.e. reciprocal, they affect each other) is yet to be fully understood.⁴

Thus, further longitudinal studies are required to better understand these relationships.^1,4

Breastfeeding and Mother's Mental Health

Mood and Stress

Scientific literature suggests breastfeeding impacts the mother’s mood and stress⁵ and vice-versa, the mother’s mood and stress levels impacts her breastfeeding activities.^{6, 4} Generally, breastfeeding is believed to be beneficial to the emotional wellbeing of the mother.^1,4

Subjective self-reports by breastfeeding mothers have reveal decreased anxiousness, negative emotions and stress in comparison to formula-feeding mothers.^5,6. A study by Brown and Lee (2011) found evidence suggesting mothers feel empowered and confident given the knowledge that breastfeeding is beneficial to their child.⁷ Research also indicates breastfeeding enhances the mother’s sleep duration, quality and reduces sleep disturbance.⁸ In a study conducted by Doan and colleagues (2007) it was found that breastfeeding mothers increased their sleep duration by an average of 45 minutes.⁸ Furthermore, the impact of breastfeeding on the mother’s mood and stress levels have been measured by observing their physiological response. Studies demonstrate breastfeeding facilitates a calmer physiological state as it enhances cardiac vagal tone modulation and lowers blood pressure and heart rate.^9,10 Furthermore, it was found that breastfeeding positively influences how mother’s respond to social situations and which consequently facilitates improved relationships and interactions.¹ Krol and colleagues (2014)  found that mothers who engage in breastfeeding respond less to negative facial expressions (e.g. anger) and increase their response to positive facial expressions (e.g. happiness).¹¹

Postpartum Depression

There is a body of research which examines the relationship between breastfeeding and postpartum depression ^{4, 12, 13}. Studies indicate breastfeeding may provide protection against postpartum depression, or help reduce some of its symptoms ^{6, 14}. Furthermore, research indicates mothers who abstain from breastfeeding or decrease breastfeeding have increased rates of depression compared to women who engage in breastfeeding^{4, 6, 15,} . On a similar note, mothers who experience postpartum depression are more likely to adopt a negative attitude towards the act.^{16, 17} and have decreased rates of breastfeeding ¹⁸ or are more likely to stop breastfeeding early on during the postpartum period^4,13.

Breastfeeding Difficulties and Postpartum Depression

Breastfeeding problems is linked with poorer maternal mood¹⁹. A common concern of mothers experiencing postpartum depression is their lack of confidence or difficulties they experience during breastfeeding ²⁰. It is suggested that mothers who have negative or difficult experiences (e.g. nipple pain) with breastfeeding may be more prone to developing postpartum depression^{21, 22, 23}. A study conducted by Nielson and colleagues (2011) reveal women who were unable to breastfeed were 2.4 times more likely to develop symptoms of depression 16 weeks after birth²⁴.  Scientists suggest mothers who experience difficulties during postpartum breastfeeding require immediate support²² or should be screened for any signs of depression²¹. Furthermore, Kielbratowska and colleagues (2015) suggest a child’s temperament may affect the breastfeeding process so mothers are encouraged to gain a deeper understanding of how infants feed during breastfeeding so potential problems may be anticipated and appropriately addressed.²⁵

Unclear Relationship between Breastfeeding and Postpartum Depression

Whilst there is research which indicates a link between breastfeeding and postpartum depression, the exact nature of this relationship is ambiguous ^1,4­. It is difficult to know whether breastfeeding causes** postpartum depression or vice versa¹_. However, it is suggested that a reciprocal or bidirectional relationship exists where postpartum depression results in reduced breastfeeding activity and early cessation, and the abstinence of or irregular breastfeeding may increase risk of developing postpartum depression. ⁴This is due to complex interactions between multiple physiological, sociocultural and psychological factors⁴. Furthermore, scientists have adopted different methods to examine this relationship which may have lead to different results.⁴ Moreover, there are conflicting results in scientific literature which have indicated no significant relationship between breastfeeding and postpartum depression, or that breastfeeding leads to increased risk of developing depression.^26,27

Mechanisms of Action

Research suggests the inverse relationship between breastfeeding and the mother’s mental health may be due to more direct causes such as the following:

• Guilt, shame and/or disappointment: Mothers who are experiencing difficulties during breastfeeding or are unable to breastfeed may feel guilt, shame and disappointment as they’re unable to provide the child with what they require. This may lead to symptoms of postpartum depression. ²⁸
• Negative opinions on breastfeeding: The mother’s perception of breastfeeding may affect her mood. Galler and colleagues (2006) found mothers with symptoms of postpartum depression were more likely to believe breastfeeding was private and restrictive.²⁹ Women who were worried about breastfeeding were also significantly more likely to be diagnosed with postpartum depression.³⁰ Depressed mothers were more likely to feel unsatisfied with breastfeeding and decreased sense of self-efficacy when it comes to breastfeeding¹³.
• Improved mother-infant bonding: Breastfeeding may also enhance the bond between the mother and child. This facilitates improved mental health.⁴

Physiological Mechanisms

Scientists have proposed theories about the underlying physiological mechanisms which facilitate the relationship between breastfeeding and the mother’s mental health.¹

The neuroendocrine mechanism of this relationship has been posited. It is suggested that the beneficial effect of breastfeeding on the mother may be due to increased levels of oxytocin during breastfeeding^1,31,32.Oxytocin levels are hypothesized to increase in both the mother’s and the infant’s brain when the infant starts to suckle in skin-to-skin contact^{33, 34}  and this hormone is known to promote relaxation and nurturing behaviour ^35,36,37 during breastfeeding. Furthermore, when experiencing stress during social situations, breastfeeding mothers demonstrate reduced cortisol response ^{4, 38} due to decreasing stress hormone levels and improving their sleep^39,. Studies have also examined neuroendocrine mechanisms related to postpartum depression and breastfeeding failure⁴⁰

In addition, according to Kendall-Tackett (2007), postpartum depression is closely associated with inflammation caused by postpartum pain or sleep deprivation. These are noted to be common experiences of motherhood. Breastfeeding is shown to decrease this inflammation response, which may have a positive effect on the mother’s mental health.²²

Breastfeeding and Child's Mental Health

Social and Emotional Health

Empirical evidence reveal links between breastfeeding and the child’s social and emotional health. Evidence suggest infants who are breastfed, compared to those who are bottle-fed, demonstrate more ‘vigour’ and intense reactions during feeding.²⁵ Furthermore, postpartum breastfeeding is found to be negatively correlated with aggression and antisocial tendencies in infants between ages 4 to 11.⁴¹ It is also suggested that this relationship carries on into adulthood. In a longitudinal study conducted by Merjonen and colleagues (2011), significant results indicated adults who were not breastfed during infancy demonstrated higher levels of hostility and aggression.⁴² However, in order to signal to their mothers to gain attention and have their needs met, breastfed infants may demonstrate fussiness and exhibit more negative expressions.⁴³ A study by Lauzon-Guillian and colleagues (2012) found children who were breastfed demonstrate more difficult temperaments. They were less emotionally stable and negative expressions (e.g. distress and frustration) occur with greater frequency whilst positive expressions (e.g. smiling and laughing) occur less often.⁴³

Mechanisms of Action

Underlying mechanisms which explain the negative correlation between breastfeeding and the child’s level of aggression or antisocial behaviour have been examined by scientists.

The physiological mechanism of this relationship is attributed to the neuroendocrine processes that occur during breastfeeding. The reduction of antisocial behaviour and aggression may be attributed to increased levels of oxytocin in the infant during breastfeeding^{1, 33,34}. Human breastmilk contains oxytocin and this hormone is further released due to physical contact and warmth during breastfeeding.^{1, 33}Increased levels of oxytocin is known to have positive effects on behaviour by promoting social and emotional development^44,45,46 and therefore decreasing levels of aggression and other antisocial behaviours.^1,47

Another possible explanation states the act of breastfeeding may be an indicator of the mother’s maternal behaviour⁴⁸. The abstinence or unnecessary prolonging of breastfeeding may suggest the mother is not mentally well and this contributes to increasingly antisocial behaviour in the child. ⁴²

Autism Spectrum Disorder (ASD)

The relationship between the development of autism spectrum disorder (ASD) and breastfeeding have been investigated.

In a study conducted by Tseng and colleagues (2017), results revealed children diagnosed with ASD were significantly less likely to have been breastfed.⁴⁹ Similarly, studies have indicated infants who were not adequately breastfed were more likely to be diagnosed with ASD.^50,51 Al-Farsi and colleagues (2012) further posit that the late initiation of breastfeeding may also increase the likelihood of the child developing ASD. These findings suggest breastfeeding may protect the child from developing ASD.⁴⁹ This association may be explained by the lack of colostrum intake from breastmilk which contains essential antibodies, protein and immune cells that are essential for typical socio-emotional development and health.⁵¹

However, research which do not show a relationship between breastfeeding and the development of ASD should be noted. Husk and Keim (2015) conducted a large-scale survey with parents of 2 to 5 year old infants and found no significant correlation between ASD development and presence/absence of breastfeeding or length of breastfeeding duration.⁵²

Furthermore, whilst correlation relationships have been indicated in some studies ^{49, 50,51}, scientists have emphasised the need to distinguish correlation from causation¹. Krol and Grossmann (2018) suggest the possibility that children who were later diagnosed with ASD may already possess behavioural traits which prevent regular breastfeeding activities.¹ For example, it has been found that children with ASD had irregular feeding patterns which were likely due to reduced joint control.⁵³ It is suggested more longitudinal studies are required to improve the understanding of breastfeeding and ASD as well as its underlying physiological mechanisms.^1,49

Mother and child mutually gaze at each other.

Breastfeeding and Mother-Child Bonding

Scientists have investigated the relationship between breastfeeding and mother-infant bonding. Breastfeeding is believed to enhance the emotional and social bond between mother and child ^{15, 35,53,21,22,23}. Breastfed infants become more dependent on their mothers and develop a deep social and emotional connection.^15,54 Similarly, breastfeeding fosters the mother’s development of a close emotional bond with their child^15,54.

In comparison with to non-breastfeeding mother-infant dyads, research indicates that in breastfeeding mother-infant dyads:

• Mothers are more responsive and sensitive to their infant’s need^58,59
• Mothers spend more time and attention their infant^15,54
• Mothers generally touch and speak to their infant more⁶⁰
• Infant’s demonstrate a greater sense of ‘attachment security⁵⁹
• Infant suckle their mother’s breast longer than with bottles^15,54,59
• The mother and infant spend more time gazing at each other²⁶ and the gaze is described as more intense^15,54

Furthermore, brain imaging research conducted by Kim and colleagues (2011) reveal breastfeeding mothers, when listening to their infant crying, demonstrate greater activity in limbic regions of the brain. This suggests the mother’s enhanced emotional, empathetic and sensitive response to their child, which further supports the notion that breastfeeding enhances mother-infant bonding⁶².

However, there are also studies which do not demonstrate a significant relationship between breastfeeding and mother-infant bonding ^{1, 63}. For example, Britton and colleagues (2006) did not find a significant association between breastfeeding and mother-infant bonding but found that mothers displayed more sensitivity were more likely to breastfeed than bottlefeed.⁶⁴ Given this, Krol and Grossman (2018) suggest the relationship between breastfeeding and mother-infant bonding may, at least partially, be due to the more direct effects of maternal sensitivity.¹ Furthermore, it is proposed that positive behaviour and enhanced emotional sensitivity generally displayed by breastfeeding mothers ^{11, 38} may improve their emotional and social bond with their child.¹