Trauma experienced by a woman in childhood can alter the composition of her breast milk and influence her child’s temperament, according to an international team of scientists from the Jagiellonian University.
The university said the discovery opens a new chapter in research on the intergenerational transmission of experiences.
The study, led by Anna Ziomkiewicz-Wichary, involved more than one hundred mothers from Wrocław and their infants.
Participants shared details of their early life experiences, including whether they had experienced violence, neglect, the loss of a loved one or other difficult circumstances.
The study focused on Adverse Childhood Experiences (ACEs), which are known to impact adult health.
“Researchers compared the breast milk composition of women with varying levels of ACE and found that those who had experienced trauma in childhood produced milk with a slightly different chemical signature. The differences primarily concerned microRNA molecules, which regulate gene activity. Although these molecules do not encode proteins, they control the mechanisms that determine which genes in the infant’s body are activated and which remain dormant,” the university said in a press release.
The team found that the milk of mothers with a history of early trauma contained higher levels of microRNA molecules associated with stress response. At the same time, their milk had lower levels of medium-chain fatty acids (MCFA), which provide energy and support the infant’s immune system. The levels of microRNA and MCFA were linked to the temperament of the children assessed at five and twelve months of age.
According to the release, infants who consumed milk with higher levels of microRNAs associated with stress response (miR-142-5p) tended to show more intense emotional reactions in moments of both joy and frustration. Children fed milk richer in MCFA were better at regulating their emotions and recovered more quickly after being upset.
“The findings suggest that milk biochemistry may be one of the mechanisms through which the effects of experience are subtly transmitted across generations. This is not a case of simple inherited stress, but rather a reflection of how the mother's body learns to respond to the world and passes on this knowledge at the molecular level,” the release said.
The researchers added that the findings mark a new direction in the study of epigenetic inheritance, or the transmission of environmental and emotional effects through changes in gene expression rather than DNA sequence.
To ensure the observed differences were not due to current living conditions, the researchers accounted for factors such as diet, BMI, feeding frequency and the mothers’ mental well-being during the postpartum period. None of these factors explained the changes in milk composition.
According to the researchers, early trauma may also affect the child through epigenetic modifications in the mother’s egg cells, the microbiome transferred during birth and maternal behaviour during pregnancy and the postpartum period.
“The study shows that our experiences, even those from many years ago, can resonate across generations. This is not proof of trauma inheritance in the literal sense, but a reminder that biology and emotion form a single, highly complex system,” the university said.
According to the Jagiellonian University, the team’s discovery opens a new chapter in research on the intergenerational transmission of experience. The researchers plan further analyses to confirm the biological mechanisms and develop diagnostic tools that could support prevention and family assistance in the future.
The study was published in the journal Translational Psychiatry. (PAP)
juka/ lm/
tr. RL
