Study suggests depressive symptoms during pregnancy lowers child immunity

The mental health of a woman during pregnancy directly influences the development of the immune system of the child, suggests a new study.

The researchers examined health records of 1,043 mother-infant pairs who are participating in the CHILD Cohort Study, which is following the health of thousands of Canadian children into their teens.

The new study was conducted by pediatric researchers at the University of Alberta.For the research, the mothers filled out regular questionnaires about their mood during and after their pregnancies.

"Our study shows that what happens to the mother during pregnancy could affect the levels and function of the cells that produce immunoglobulin in children," said Anita Kozyrskyj, a pediatric epidemiologist and a leading researcher on gut microbes.

Stool samples from the babies were examined for the presence of intestinal secretory immunoglobulin A (sIgA), an antibody that plays a crucial role in immunity.

"This immunoglobulin is really important in the microbiome for developing oral tolerance to environmental antigens," said lead author Liane Kang, who carried out the research for her MSc and is now studying medicine at the U of A.

Mothers who reported symptoms of depression during their third trimester, or persistently before and after the birth, were twice as likely to have babies with the lowest levels of immunoglobulin A in their gut.

The mothers' symptoms did not have to be severe enough for a clinical diagnosis of depression. No link was found with postpartum depression.

The results held true even when variable factors such as breastfeeding and antibiotic use by the mothers and babies were taken into account.

The researchers said lowered immunity places the babies at risk for respiratory or gastrointestinal infections, as well as asthma and allergies, and may also lead to elevated risk for depression, obesity and autoimmune diseases such as diabetes.

Kozyrskyj posited that higher levels of the stress hormone cortisol may be transferred from depressed mothers to their fetuses and interfere with the production of cells that will make immunoglobulin after birth. She suggested more research is needed to understand this link between the maternal microbiome and infant immune development.

Both researchers said their study indicates that more mental health supports are needed for pregnant women.