Since ancient times, scientists have written about beliefs that the emotional state of the pregnant mother may affect her unborn child. Today, both animal and human studies support the notion that maternal stress and anxiety during pregnancy can have both immediate and long-term effects on her offspring. However, studies vary substantially in terms of their methodologies and results. Some studies examine isolated stressors, such as death of a spouse or natural disaster, while others look at stressful feelings and daily hassles during pregnancy.