Prenatal stress: Effects on fetal and child brain development

The impact of stress on brain health begins in the womb. Both animal and human studies have found that prenatal maternal stress affects the brain and behavior of the offspring. Stressful life events, exposure to a natural disaster, and symptoms of maternal anxiety and depression increase the risk for the child having a range of emotional, behavioral and/or cognitive problems in later life. These include depression, anxiety, Attention Deficit Hyperactivity Disorder (ADHD), and/or conduct disorders. There is an increased risk for other outcomes also, including preterm delivery and reduced telomere length, possibly indicative of an accelerated life history. The causal role of prenatal maternal stress on the etiology of the neurodevelopmental disorders is supported by large population cohorts, which have controlled for a wide range of potential confounders, including postnatal maternal mood. More recently, research has begun to explore the biological correlates and mediators of these findings. These studies suggest that the hypothalamic pituitary adrenal (HPA) axis plays a role in mediating the effects of maternal stress on the fetal brain. Further, in vivo brain imaging research reports that maternal stress is associated with changes in limbic and frontotemporal networks, and the functional and microstructural connections linking them. The structural changes include cortical thinning and an enlarged amygdala. While these studies have been conducted on smaller sample sizes and could not control for many confounders, the observed brain changes do plausibly underlie many of the emotional, behavioral and cognitive changes found to be associated with prenatal stress.