ABSTRACT-The notion that a woman's psychological state during pregnancy affects the fetus is a persistent cultural belief in many parts of the world. Recent results indicate that prenatal maternal distress in rodents and nonhuman primates negatively influences long-term learning, motor development, and behavior in their offspring. The applicability of these findings to human pregnancy and child development is considered in this article. Potential mechanisms through which maternal psychological functioning may alter development of the fetal nervous system are being identified by current research, but it is premature to conclude that maternal prenatal stress has negative consequences for child development. Mild stress may be a necessary condition for optimal development