A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Winter, 2017 | Number 1, Volume 31

Mother’s allergies during pregnancy could alter fetal brain

Maternal allergies during pregnancy may play a role in neurological conditions such as autism and ADHD, a new study suggests. Kathryn Lenz and her colleagues sensitized female rats to ovalbumin, a protein found in egg whites, before the rats became pregnant. Fifteen days into pregnancy, the rats were exposed to the allergen, triggering an immune response. 

The researchers found that both male and female offspring of these rats had increased numbers of immune cells in the brain called mast cells and reduced numbers of a different type of immune cells called microglia. The offspring of allergic mothers were also hyperactive, demonstrated less anxiety-like behavior, and engaged in less “rough and tumble” play. 

Lenz says, “The males born to the allergen-exposed mothers looked more like females. They were more socially reserved. They were really hyperactive but socially disengaged. That looks a bit like ADHD.” In addition, rats born to allergic mothers exhibited less mental flexibility than control rats. (To test mental flexibility, the researchers hid Cheerios in terra-cotta pots, concealing them in different ways.) Both male and female offspring of allergic mothers had difficulty with mental flexibility, with males showing the most marked impairment. 

Lenz and her team also examined the density of dendritic spines in the rats’ frontal cortexes. These synaptic connections are crucial for communication between brain cells. The researchers found that male offspring of allergen-exposed mothers had a reduced number of dendrites, while females had an increased number. 

Lenz concludes, “This is evidence that prenatal exposure to allergens alters brain development and function and that could be an under-appreciated factor in the development of neurodevelopmental disorders.”


“Allergies during pregnancy contribute to changes in the brains of rat offspring,” Misti Crane, news release, Ohio State University, November 16, 2016. Lenz and her team presented their findings at Neuros cience 2016 on November 16, 2016.