Prenatal Maternal Stress and the Developing Fetus and Infant: A Review of Animal Models as Related to Human Research

Abstract

Prenatal stress, a function of severe maternal psychological or physiological stress, including trauma and illness, can influence the development of the fetus in profound ways, extending into childhood and adulthood. Maternal trauma, acute and chronic, physiological and emotional, can create an environment for the fetus that may disrupt development in the womb, potentially setting the infant on a path of maladaptive reactivity to stressors in the world beyond. Prenatal stress influences psychological systems, including attachment, affect, and stress regulation; physiological systems, including endocrine and cardiovascular systems; and even neuroanatomical structure. This article reviews some of the findings from animal models associated with this important line of research and indicates the critical nature of early intervention for families such as those described in this issue on the Project for Mothers, Infants, and Young Children of September 11, 2001.

Notes

1. A phenotype of a particular animal is made up of both gene expression and the influence of environmental factors, as well as any possible interactions. By contrast, an animal's genotype is comprised of inherited genetic information. Animals with the same genotype can appear very different from one another because both behavior and appearance are altered by environmental and developmental influences.

2. The “diathesis-stress” model explains the appearance of certain diseases and behaviors as the combined result of genetic factors or pre-existing vulnerable conditions (diathesis), and environmental influences (stress); that is, nature and nurture. The model is particularly useful in treatment models that incorporate stress-reduction and environmental controls as a way to mitigate genetic predisposition to illness and disease. It has been expanded to include a discussion of protective factors, which allows for a more nuanced understanding of when and why disease manifests itself (Mrazek & Haggert, 1994).

3. The hypothalamic-pituitary-adrenal axis (HPA axis) consists of the hypothalamus, the pituitary gland and the adrenal gland, all part of the body's endocrine system which regulates hormone levels. Using a negative feedback loop, the HPA axis releases and regulates the steroid hormones known as glucocorticoids (cortisol in humans; corticosterone in rodents). Glucocorticoids, together with the epinephrine and norepinephrine secreted by the sympathetic nervous system, generate the majority of the physiological changes induced by stress throughout the body. Unlike epinephrine and norepinephrine, which act on a rapid, split-second basis in the bloodstream generating a “fight or flight” response, glucocorticoids cross the blood-brain barrier and manage the stress response on a slower, minute-by-minute to hourly basis, causing sustained behavioral responses.