Q&A: Stress fluctuations during pregnancy associated with negative emotions in infants

Key takeaways

• Greater stress fluctuations during pregnancy were linked to more distress, fear and sadness among infants.
• Stress levels were not related to the COVID-19 pandemic.
• More research is needed to better understand the causes of stress fluctuations.

Having more extreme fluctuations in stress during pregnancy correlated with more feelings of distress, fear and sadness among infants, according to a recent study.

Researchers said the findings highlight the need to further explore the link between prenatal stress and neurodevelopmental outcomes among infants.

The study, published in Infancy, is the first to measure the “ebbs and flows of stress,” according to a press release. Although research often looks at stress “as a static, unchanging construct — one that is either high or low, present or absent,” Leigha MacNeill, PhD, a research assistant professor at Northwestern University, said in the release, “that variability is inherent in our daily lives.”

The analysis included 72 women who participated in frequent surveys during pregnancy — up to four times a day for 14 weeks — and a temperament questionnaire when their children were 3 months old. Using these data, MacNeill and colleagues determined “that mothers with greater variation in stress from moment to moment across the 14-week period during pregnancy had infants with higher levels of temperamental negative affect early in life.”

The researchers said they “leveraged the COVID-19 pandemic as a natural experiment.” Some participants took their initial surveys when the pandemic began, and some took them during the pandemic. Regardless, the study revealed that stress patterns in pregnant people were unrelated to the pandemic’s timing.

Healio spoke with MacNeill to learn more about the findings, the differences between chronic and fluctuating stress, and more.

Healio: This study was conducted during the pandemic — inarguably a time of increased stress, and certainly for pregnant people. Do you think this affected the results?

MacNeill: The pandemic continues to be an evolving situation — March 2020 looked really different than March 2021. Given the small number of participants, we weren't able to test whether fluctuations in stress during pregnancy differed depending on when during the pandemic stress was measured, such as around the initial stay-at-home order or around the vaccine roll-out. I think we could have possibly seen different patterns of stress at different timepoints during the pandemic. Looking at stress patterns in larger, more diverse samples is an important next step to see if these findings replicate, if they differ depending on when in the pandemic the stress was measured, and if different groups have been disproportionately affected by the pandemic.

Healio: You wrote that there are likely complex pathways from prenatal stress exposure to infant socioemotional development. Would you expand on that?

MacNeill: There is a lot of emerging research on how stress during pregnancy alters the physiological structure of the developing fetus, which in turn impacts infant brain and behavior development. Yet, how these processes operate over time are not well understood. Stress itself is a complex process, made up of biological functioning, psychological states and emotional responses, and an individual’s tendency to perceive, experience, and manage their stress. And not all stress is bad — mild or fleeting stress helps us navigate situations safely and with care. We’re still figuring out the characteristics and timing of stress that matter most for maternal and child health and well-being. The current study, like many other studies, was not causal, and it’s challenging to determine how or whether different aspects of the maternal prenatal experience cause aspects of the child's emotional development.

Healio: How is fluctuating stress different from sustained, generalized stress? Do the two have differing outcomes for infants?

MacNeill: Fluctuations in stress may reflect some instability in the pregnant person’s life circumstances, instability in how the pregnant person deals with stress, an overall difficulty in regulating emotions, or some other process. In the current study, we found that those fluctuations, and not typical levels of stress over pregnancy, were linked to more negative emotions in infants. A key next step in this research is to better understand what causes those fluctuations in stress (eg, stressful life events, underlying physiology) so we may better help expecting parents.

Healio: Conflicting with previous research, the study found no difference in baseline stress for people who completed the initial survey before or during the pandemic. However, you note in the study that many of the participants were highly educated, middle to upper class and partnered, which could be a possible explanation for this. In a larger, more diverse study, would you anticipate associations with other sociodemographic factors, like annual income?

MacNeill: I anticipate we may see differences in stress patterns for different sociodemographic groups.

Healio: What is the take-home message for primary care providers?

MacNeill: Many pregnant individuals receive some prenatal care during pregnancy, so assessing stress, monitoring stress and providing resources for managing stress at these visits could help minimize stress during pregnancy. Routine stress screening and management should also continue postpartum. Maternal and family health and well-being need to be in place for child health and well-being, and I hope these findings contribute to the growing spotlight on the need for policies that support families.

References:

• MacNeill LA, et al. Infancy. 2022;doi:10.1111/infa.12499.
• Mothers’ stress rollercoaster while pregnant linked to negative emotions in babies. https://www.eurekalert.org/news-releases/955140. Published Sept. 7, 2022. Accessed Sept. 7, 2022.