While it is known that a mother’s health during pregnancy can  impact the health of her future offspring, new research suggests that a father’s health— specifically his stress levels— can also play a role. Researchers from the University of Maryland’s School of Medicine have found, in a mice study, that stress changes men’s sperm, which can then alter the brain development of future children.

The study could lead to a better understanding of the key role that fathers play in the brain development of children.

Tracy Bale, a neuroscientist from the University of Maryland’s School of Medicine, presented the research on Feb. 16 during the 2018 American Association for the Advancement of Science (AAAS) Annual Meeting in Austin, TX.

Scientists already knew that factors like poor diet, stress and infection in mothers during pregnancy, can cause damage and negatively affect the offspring. This is likely because the environment affects the expression of certain genes—called epigenetics.

However, the researchers found that a father’s stress could also affect offspring development by altering important aspects of his sperm.

Bale previously discovered that adult male mice experiencing chronic periods of mild stress have offspring with a reduced response to stress. Changes in stress reactivity have often been linked to neuropsychiatric disorders such as depression and post-traumatic stress disorder.

For this study, the researchers isolated the mechanism of the reduced response and found that the father’s sperm showed changes in genetic material called microRNA—which plays a role in which genes become functional proteins. 

The researchers found that in the male reproductive tract, where the sperm matures—the caput epididymis—releases tiny vesicles packed with microRNA that can fuse with sperm to change its cargo delivered to the egg. The caput epididymis responded to the father's stress by altering the content of these vesicles.

The researchers suggest that even mild environmental challenges can have a significant impact on the development and potentially the health of future offspring. A better understanding of the links between a father’s exposure to stress and the risks of disease for the offspring could lead to new methods to detect and prevent certain disorders.

Bale has focused much of her research on the links between stress and subsequent risk for neurodevelopmental disorders, including autism and schizophrenia, in offspring. Her previous studies on the placenta have revealed novel sex differences during pregnancy that may predict increased prenatal risk for neurodevelopmental disorders in males.