The daily stresses of parenthood, especially for new moms, consist of worries over providing proper nutrition, keeping the baby in good health, and being financially stable to support the new addition to the family. While deadlines at work, or even relationship issues, can add on to the stresses of motherhood, it is important to remain calm — for the baby’s health. According to a recent study, published in the journal Psychological Science, mothers’ stress may be “contagious” to babies due to their ability to pick up on their parents’ change of voice tone, touch, and smell during stressful situations.

Doctors have expressed great concern over the prevalence of frequent or continual stress on young children. Toxic stress in kids may result from daily exposure to very difficult situations such as witnessing violence or trauma, or having a family member with mental health or substance abuse issues. The American Academy of Pediatrics has called for major changes to checkups of the future by suggesting primary care doctors screen their youngest patients for social and emotional difficulties — early signs of toxic stress. These new screenings could help reduce medical issues ranging from heart disease to drug abuse, which are often triggered by toxic stress. The focus on a child’s brain is essential to determine their social and emotional state at a young age.

The release of stress hormones in infants may alter the connection of brain circuits. Exposure to high levels of stress at such a young age can disrupt early brain development — resulting in the development of a smaller brain — and compromise the functioning of the nervous and immune systems, says the Centers for Disease Control and Prevention. In addition, childhood stress can lead to health problems including alcoholism, depression, cancer, and other chronic diseases.

People learn how to manage stress and other strong negative emotions in their daily lives in the parent-child relationship. While it is known emotions, like stress, can be transmitted from one person to another — such as romantic partners — a team of researchers sought to examine emotional synchrony between mother and child. Sixty-nine mothers and their 12- to 14-month-old babies were recruited to participate in the study. The babies’ emotion and heart rate were examined when their mothers were put through a stressful task.

Cardiovascular sensors were attached to both mother and infant so the researchers could take baseline recordings from each. The mothers and babies were separated so that the mothers could give a five-minute speech and go through a five-minute Q&A. Every mother’s speech and Q&A session was reviewed by an evaluator who either gave positive, negative, or no feedback.

The findings revealed the mothers who received the negative feedback had more negative emotions and fewer positive emotions, including increased cardiac stress. Moreover, when the researchers reunited the mothers with their babies, within minutes the babies picked up on their mother’s stress by showing signs of increased cardiac stress; the greater the mother’s stress, the greater the baby’s response.

"Our research shows that infants 'catch' and embody the physiological residue of their mothers' stressful experiences," said Sara Waters, lead researcher and postdoctoral scholar at the University of California, San Francisco, in the news release. "Your infant may not be able to tell you that you seem stressed or ask you what is wrong, but our work shows that, as soon as she is in your arms, she is picking up on the bodily responses accompanying your emotional state and immediately begins to feel in her own body your own negative emotion."

Emotional contagion may be communicated via odor, vocal tension, and facial expressions. Babies are extremely sensitive to their parents’ emotions and moods because of their perceptive social barometers. They have the ability quickly pick up the parental vibes and soon begin to adopt those feelings as their own.

In a similar study published in the journal Psychological Science, researchers found babies who are exposed to arguments between parents in the home respond to angry tone of voice, even when they’re asleep. The stress and negative emotions present in the environment were associated with how infants’ brains function. The greater the conflict, the greater brain reactivity shown in brain areas linked to stress and emotion regulation. Babies’ brains are highly plastic, and this allows them to develop in response to the environments and encounters they experience on a day-to-day basis.

Both studies highlight the long-term impact stress and other negative emotions can have on the health and well-being of infants as they get older. Parents who wish to manage their stress should develop good coping tools to not overwhelm or stress their baby beyond the inevitable. Therefore, the calmer a parent is, the calmer the baby will be, which will lead to healthy development.

Sources:

Mendes WB, Waters SF, West TV. Stress Contagion: Physiological Covariation Between Mothers and Infants. Psychological Science. 2014.

Fisher PA, Graham AM, and Pfeifer JH. What Sleeping Babies Hear: A Functional MRI Study of Interparental Conflict and Infants’ Emotion Processing. Psychological Science. 2013.