Stress in pregnancy affects immunity of unborn child

Pregnancy is a time of joy for most families. However, it can burden some women, causing them to suffer from high stress levels or depression.

While most people have been socialised to believe that the stress is a normal experience for expectant women, health experts caution against it due to the adverse effects the suffering can have on the mother and the unborn child.

A new study conducted by paediatric researchers from the University of Alberta has found that women's mental health during pregnancy has a direct influence on the development of their children’s immune system.

According to the research, which was published in the Clinical & Experimental Allergy Journal, high stress levels experienced by expectant mothers can affect the production of immunoglobulins (antibodies) that play an essential role in the body's immune system.

The antibodies usually attach to foreign substances such as bacteria or viruses and assist in destroying them.

"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 paediatric epidemiologist and a leading researcher on gut microbes who was part of the research team.

Past studies have revealed that children of pregnant women that suffered from depression during pregnancy have a higher risk of developing asthma and allergies due to low immunity.

The reasons behind the adverse impact of mental health problems on the immunity of children have eluded scientists for years.

The new study, which is the first of its kind to be conducted in humans, sought to identify the mechanism at work.

During the study, the researchers examined health records of 1,043 mothers and their babies in Canada.

To determine the mental state of women at the time when they were expectant, the mothers filled out regular questionnaires that sought to ascertain their mood during and after their pregnancies.

Some of the questions sought to find out if the mothers had felt sad or overwhelmed at the specified time.

The researchers also took stool samples from the babies and examined them for the presence of an antibody known as immunoglobulin A that plays a crucial role in immunity. It is the first line of defence that offers the body resistance against diseases.

"It is really important for developing oral tolerance to environmental antigens [disease causing bugs]," said Liane Kang, the lead author of the study.

The results of the study showed that mothers who reported symptoms of depression during their third trimester, or persistently before and after birth, were twice as likely to have babies with the lowest levels of essential immunoglobulin A antibodies in their gut.

Based on the findings, the mothers’ symptoms did not have to be severe enough (to warrant a clinical diagnosis of depression) for the stress to adversely affect their babies’ immunity.

In addition, the lowest levels of immunoglobulin A antibodies were found in infants between four and eight months old. This is the period when they would normally begin to produce their own antibodies.

"The largest impact of depression in the mothers was seen in this start-up phase of the child's own immune system," said Kang.

According to the researchers, lowered immunity places babies at risk for respiratory or gastrointestinal infections, as well as asthma and allergies.

It may also increase the children’s chances of getting depression, obesity and autoimmune diseases such as diabetes.

Kozyrskyj states that the impact of maternal stress on unborn children could be due to higher levels of the stress hormone (cortisol) bring transferred from depressed mothers to their foetuses.

This interferes with the production of cells that are essential in boosting children’s immunity after birth.

Consequently, the researchers said that their study indicates that more mental health support is needed for pregnant women.

"New mothers are going through a very different stage in their life where they have to take care of another human being, and there are a lot of stressors that come with that," said Kang.

However, these findings should not be used to blame mothers," said Kozyrskyj. "Maternal mental health does not occur in isolation."

To avert stress, pregnant women are encouraged to embrace healthy diets, get sufficient sleep and do moderate physical exercises.

When dealing with stressful situations, it is important to identify what is causing the problem and take practical steps to address the challenge.

People are advised against responding to stress in negative ways such as withdrawing from people, sleeping to escape problems, skipping meals or eating junk food, and using alcohol and tobacco.

It is important to be surrounded by loving and supporting people, as well as to reach out for help when feeling overwhelmed by the pregnancy. Opening up and talking about the challenges with trusted family members, relatives and friends is also helpful.

Nevertheless, pregnant women are encouraged to seek professional help from doctors or health practitioners if stressful experiences become persistent and overwhelming as they could be suffering from depression.

Some of the major symptoms of depression include: sleep problems, appetite loss, sadness, crying frequently, lack of interest in normally enjoyable activities, or excessive feelings of guilt that occur for more than two weeks.