Study Suggests That Stress Endured by Pregnant Women May Alter the Genes of Their Children and Grandchildren

A new study led by Veena Prahlad, an associate professor of biology at the University of Iowa finds that stress endured by a pregnant woman may genetically alter not only her children but her grandchildren as well.

Dr. Prahlad and her team of researchers looked at how a mother roundworm reacts when she senses danger, such as a change in temperature, which can be harmful or even fatal to the animal. They discovered a mother roundworm releases serotonin when she senses danger. The serotonin travels from her central nervous system to warn her unfertilized eggs, where the warning is stored, so to speak, and then passed to offspring after conception.

“Genes have ‘memories’ of past environmental conditions that, in turn, affect their expression even after these conditions have changed,” Dr. Prahlad explains. “How this ‘memory’ is established and how it persists past fertilization, embryogenesis, and after the embryo develops into adults is not clear. This is because during embryogenesis, most organisms typically reset any changes that have been made to genes because of the genes’ past activity.”

“What we found all the more remarkable was that if the mother was exposed to stress for a short period of time, only progeny that developed from her germ cells that were subjected to this stress in utero had this memory,” Dr. Prahlad says. “The progeny of these progeny (the mother’s grandchildren) had lost this memory. However, if the mother was subjected to a longer period of stress, the grandchildren generation retained this memory. Somehow the ‘dose’ of maternal stress exposure is recorded in the population.”

In theory, the effects of stress on pregnant humans may also be passed on genetically. Studies have shown that pregnant women affected by famine in the Netherlands from 1944 to 1945, known as the Dutch Hunger Winter, gave birth to children who were influenced by that episode as adults — with higher rates than average of obesity, diabetes, and schizophrenia.

Dr. Prahlad earned her undergraduate degree at St. Joseph’s College in Bangalore, India in 1990. In 1992, she earned a master’s degree in life sciences from Jawaharlal Nehru University in New Delhi, India. She holds a Ph.D. from Northwestern University in Evanston, Illinois.