Study Shows Prenatal Stressors Are Independently Associated With More Infant Inflexibility

STONY BROOK, NY, March 24, 2026 - A study of 1,585 pregnant women during the Covid-19 era reveals that prenatal risk as defined by a multitude of maternal psychosocial stressors is associated with greater infant inflexibility and difficulty with routines during a baby's first year of life. Led by Stony Brook Medicine researcher Heidi Preis, MSW, PhD, the study findings illustrate that stress experienced during pregnancy clearly impacts the socioemotional development of babies, even after accounting for postpartum experiences of stress. The findings are explained in a paper published in Infant and Child Development.

Studies have shown that infant socioemotional development has cascading effects on childhood into adulthood, which makes identification of early risk factors a priority for clinical research and care of children. The fetal programming hypothesis suggests that the in-utero environment can alter fetal development and have lasting effects on health outcomes, such as socioemotional development. It is therefore critical to uncover which prenatal conditions, including psychosocial stressors, can influence child development via changes in maternal physiology.

This study is unique in that it assesses multiple types of prenatal stress simultaneously, rather than focusing on a single maternal experience such as anxiety or depression. Women participating in the study ranged from 19 to 45 years of age.

The research team assessed prenatal and early postpartum risk by way of six stressful conditions- maternal anxiety, maternal depression, financial hardships, insufficient partner support, pregnancy-specific stress and pandemic-related stress. They assessed the impacts of stress on infant socioemotional development through a series of participant surveys throughout the prenatal and postpartum periods. In their analysis, the researchers examined the differential effects of prenatal and postpartum stress, along with clinical conditions. This allowed them to confidently say, that while the effect is small, stress experienced during pregnancy, can impact the growing fetus, manifesting through socioemotional development.

"Stress experienced during pregnancy, whether emotional, financial, relational, or pandemic-related, was linked to babies being more inflexible and having more trouble with routines around 11 months of age compared to babies whose mothers did not have multiple stressors," summarizes Dr. Preis, Associate Professor of Research in the Department of Obstetrics, Gynecology and Reproductive Medicine in the Renaissance School of Medicine (RSOM) at Stony Brook University. She is also an affiliate faculty member of the Program in Public Health and Department of Psychology at Stony Brook University.

"Importantly, these patterns held with the babies even after accounting for any level of stress after birth mothers felt, meaning that the womb environment has its own distinct influence on children," she adds.

Interestingly, infant irritability was associated with postpartum risk but not with prenatal stressor risk factors. Also, when mothers experienced both high pregnancy and postpartum stress, infants showed the greatest difficulties. Some specific stressors, namely low partner support and pregnancy-specific worries, had close associations to babies' difficulties with routines. Such findings may point toward early interventional targets to reduce stress in pregnancy and offer support to postpartum women.

The research was supported in part by funding from the National Institutes of Health (grant number R21DA049827).