By John Salak —
Stress isn’t just an increasingly debilitating danger for the living. It can also affect those waiting for birth, especially if pregnant moms experience significant fluctuations in their stress levels.
Women who face extreme swings in stress while pregnant—also called lability—tend to have infants who experience more fear, sadness and distress at three months than babies whose moms embraced more stable stress levels, according to Northwestern University.
It isn’t the first study to examine the emotional impact of a pregnant mother’s stability on their newborn. But Northwestern’s work is one of the first studies to measure it in real-time, which enabled a closer look at whether changes in a mother’s stress during pregnancy impact infant development.
“Research often examines stress as a static, unchanging construct—one that is either high or low, present or absent. Most of us have a lot of ebbs and flows in our stress depending on what is around us,” explained lead study author Leigha MacNeill, an assistant professor at the university’s school of medicine. “That variability is inherent in our daily lives, so this lability is capturing an important aspect of stress and offers insight into how to measure stress going forward.”
Two pregnant women may have the same average stress level during pregnancy but can experience significantly different swings in stress levels, which could impact their unborn children’s emotional development.
“There may be something about that gestational experience when a mother moves between extremes that shapes the child’s disposition toward negative emotions,” MacNeill said. “That stress pattern could reflect instability in daily life experiences, unpredictable external stressors or instability in how a mother perceives her lived experiences, which may have important implications for children’s emotional development.”
Getting a better handle on how these swings impact a child can lead to the development of prenatal programs that can help women better cope with stress fluctuations to benefit their child, said MacNeill.
The university’s study measured pregnant individuals’ stress four times daily for 14 weeks using questions sent to participants’ phones. The responses allowed researchers to identify three types of stress: first assessment (baseline), typical stress across the 14 weeks, and the number of stress levels changed from one time to the next across the 14 weeks (lability).
The researchers also measured infants’ negative emotions via a temperament questionnaire given to mothers when their infants were three months old.
“This is an early index, so we’d want to see how consistent their negative affect levels are in the first year of life,” MacNeill said. “Parents are the ones who can soothe their infants and be responsive to their needs, and as infants grow, there are things parents can do to help the child navigate situations and learn to regulate and cope with their negative emotions.”
The research also shows the connections between mothers and their unborn children, added Dr. Matthew Davis, chair of the department of pediatrics at Feinberg and the Ann & Robert H. Lurie Children’s Hospital of Chicago.
“This study illustrates that the links between parent and child are genes and experiences, even before birth. One of the most important approaches to having a less distressed child is to support expectant parents and minimize their stress during pregnancy. That can be accomplished through clinical care, social supports and policies that are family- and pregnancy-friendly,” added Davis, who was not directly involved with the study.
MacNeill noted there needs to be more research to determine how infant stress levels fare past the three-month mark to determine the potential longterm-impacts of a mother’s stress levels on their children. However, an earlier study out of the University of California San Francisco revealed that expectant mothers who participated in mindfulness-based programs had children who responded relatively well to stress at six months old compared to infants of moms who didn’t get involved in these programs.
This is the first known study to show that a prenatal social intervention may improve health outcomes in offspring, as measured by autonomic nervous system responses, reported Amanda Noroña-Zhou, the study’s first author.
“It is well established that maternal stress in pregnancy increases the risk for health problems in the children,” explained Noroña-Zhou. “But we haven’t understood how this process unfolds and the biological mechanisms underlying it, or whether we can buffer the effects of stress on negative health outcomes.”
The UC-San Francisco researchers examined 135 mother-infant connections from low-income, racially and ethnically diverse backgrounds who were experiencing high stress in their lives. Infants whose mothers underwent an eight-week mindfulness-based program had a faster cardiovascular recovery from stressful interactions and more self-soothing behavior than those who didn’t.
“There has been so little research on what we can do in the positive lane; it’s been mostly about showing the negative effects of prenatal stress,” said Nicki Bush, the study’s senior author. “This is the next frontier—interventions for moms that have positive effects on both mom and baby.”
The mindfulness program helped the babies respond better to stressful situations and recover more easily once conditions return to normal.
“A strong reaction and quick recovery are healthy because we want our bodies to be ready for action when something is wrong, then go back to normal easily,” Bush said. “The babies whose mothers did not receive the intervention had a more delayed response. They didn’t respond strongly until the threat had passed, and then they didn’t calm down easily after the threat was over.”
The results of UC-San Francisco study could have far-reaching personal and societal consequences,” the researchers claimed. “Pregnancy is an incredible window of opportunity for both mothers and babies,” said Bush. “We could, as a society, save a lot of money while doing the right thing for the next generation.”