Studies: Baby monkeys whose mothers were exposed to a major stress while pregnant show the signs of that stress in their temperament, displaying an inhibited temperament reflected in altered levels of noradrenaline and dopamine. (Quartz, Steven R., PhD, and Terrence J. Sejnowski, PhD. Liars, Lovers, and Heroes. p 126. NY: HarperCollins Publishers Inc., 2002.)
Refer to Stress and the Brain for additional information.