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New Study: Chronic Stress During Pregnancy Increases Risk for Postpartum Depression

Originally posted October 15, 2012.

Benedetta Leuner, assistant professor of psychology and neuroscience at Ohio State University, released a new study on Saturday, 10/13/2012, during a talk at Neuroscience 2012, the annual meeting of the Society for Neuroscience, in New Orleans.

Using rats, Leuner and her colleagues study the effects of pregnancy on the brain. In a study released last year, Leuner and her colleagues found that the brains of unstressed new rat mothers had a 20% increase in neuronal connections in some brain regions, allowing for increased flexibility in thinking and behaviors: multitasking.

As we already know, at a brain level, learning is actually growth and strengthening connection between neurons (Hannaford, 1995). For example, a habitual act, such as driving, is the creation, eventual connection and the bundling with myelin, of many neurons. The plasticity of the brain, the ability to learn and bundle new neurons results in flexibility of thought and behavior.

The study this year, done by Leuner and her colleagues, shows that new rat mothers, who had been stressed during pregnancy, do not show the increase in neuronal connections in their brains. The stressed rats gained weight, had an increase in size of their adrenal glands, gave birth to smaller pups and were generally not good mothers. The researchers are not sure of the mechanism that inhibits dendritic growth in the brains of stressed rate mothers.

However, this study supports the hypothesis that chronic stress during pregnancy is a risk factor to develop postpartum depression.

Chronic stress, such as poverty, famine, and natural disasters are known to affect human mothers, and to be a risk factor for preterm birth, low birth weight and postpartum depression. The decrease in the ability to mother is devastating to mother and child, and has an impact on society as a whole.

So our grandmothers who told us to take it easy during pregnancy were on the right track!

Managing stress, practicing relaxation and awareness practices during pregnancy, enhances pregnancy.

For more information about stress and pregnancy read : How much stress is too much stress during pregnancy?


Hannaford, C. (1995). Smart moves: Why learning ins not all in your head. New York: McGraw-Hill.


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