Breastfeeding, Brain Activation to Own Infant Cry, and Maternal Sensitivity

Kim, P., Feldman, R., Mayes, L. C., Eicher, V., Thompson, N., Leckman, J. F., & Swain, J. E. (2011). Breastfeeding, brain activation to own infant cry, and maternal sensitivity. Journal of Child Psychology and Psychiatry, 52(8), 907-915.

Breastfeeding changed the mother’s brain, activating brain regions associated with empathy, greater maternal sensitivity, and mother-infant bonding.

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Sample

  • N: 17
  • Subject Ages: Infants 2 to 4 weeks postpartum
  • Location: United States, New Haven, Connecticut
  • SES: Not available
  • Eligibility: Biological mothers with full-term, healthy infants
  • Additional: All mothers were Caucasian and married or cohabiting

Hypotheses

  1. Brain regions related to maternal behaviors including the hypothalamus, midbrain, amygdala, striatum, cingulate cortex and prefrontal cortex would show greater activation in breastfeeding mothers relative to formula-feeding mothers in response to own baby-cry.
  2. Breastfeeding mothers would show greater levels of maternal sensitivity at three months postpartum.
  3. The level of brain activity in response to own baby-cry at the first month postpartum would be associated with maternal sensitivity in dyadic interactions videotaped at three to four months postpartum.

Variables Measured, Instruments Used

  • Maternal brain activation in response to her own baby’s cry versus control baby-cry one month postpartum - fMRI scanning
  • Maternal sensitivity - videotaped in the home three to four months postpartum and coded with the Coding Interactive Behavior (CIB) Manual (Feldman, 1998)

Design—Descriptive

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Findings

  1. In the first postpartum month, breastfeeding mothers showed greater activations in the superior frontal gyrus, insula, precuneus, striatum and amygdala while listening to their own baby-cry as compared to formula-feeding mothers.
  2. For both breastfeeding and formula-feeding mothers, greater activations in the right superior frontal gyrus and amygdala were associated with higher maternal sensitivity at three to four months postpartum.
  3. Results suggest links between breastfeeding and greater response to infant cues in brain regions implicated in maternal-infant bonding and empathy during the early postpartum. Such brain activations may facilitate greater maternal sensitivity as infants enter their social world.
  4. First evidence using brain imaging that breastfeeding at the first month postpartum has a significant link to both enhanced maternal brain responses to infant stimuli and maternal behaviors.

Limitations

  • Small sample 
  • Although infant cries from the two groups and the control infant cry were rated as having a similar level of emotional intensity by independent raters, because mothers selected samples of their own babies' cries by themselves, it is possible that one group of mothers may have selected cry samples that they perceived as being more emotionally salient.
  • No measure for maternal sensitivity at two to four weeks postpartum when the brain responses to infant stimuli were assessed
  • Because factors related to a mother’s decision to breastfeed may also be associated with these parental outcomes, future research is needed to understand whether breastfeeding moderates the relationship between a mother’s decision to breastfeed and neurological responses to her infant with pre- and post-intervention studies.
  • More research is also required to examine whether the increase in brain response related to breastfeeding and the significant associations between early maternal brain responses and later parenting behaviors influence the infant’s cognitive, social and emotional development.