Do stressed mothers have heavier children?

The fact that too much stress can lead to an unhealthy diet is well known. It may prompt us to reach for a piece of chocolate to soothe our nerves, pop a frozen pizza in the oven to save time, or quickly take a sip of soda.

However, we have recently learned that maternal stress has a negative effect on the weight of small children. “Especially during the first years of life, childhood development is very sensitive to external influences that can lead to the child becoming overweight. This also includes psychological influences such as maternal stress,” says Dr. Kristin Junge, nutritionist at the Helmholtz Centre for Environmental Research (UFZ). Along with colleagues from the University of Bristol and the Berlin Institute for Health (BIH), she interviewed nearly five hundred mother-child pairs and then published the results in the journal BMC Public Health.

The mother-child data originate from the LiNA-Studie, which UFZ jointly coordinates with clinical partners in Leipzig. This long-term study has been investigating childhood development phases since 2006, focusing on lifestyle, environmental pollution, and incidence of allergies, respiratory diseases, and excess weight.

The research team calculated the children’s body mass index (BMI) up until the age of five from the data on height and weight, and compared this with the stress experienced by the mothers during pregnancy and the first two years postpartum. They surveyed the stress level using a questionnaire in which the women gave information about their worries, fears, feelings of tension, their general satisfaction, and how they handle daily demands.

And indeed, the researchers found a link between maternal stress and the weight gain of their children, especially during the first twelve months after birth. “We could clearly see that there is a connection between the stress felt by the mother during the first year of the child’s life and the child’s weight development during the first five years,” says Dr. Irina Lehmann, Professor of Environmental Epigenetics and Lung Research at BIH and one of the leaders of the study. “Stressed mothers are more likely to have overweight children than relaxed mothers.”

The first year of life seems to be a particularly sensitive phase. “This time period is the best indicator of whether children will tend to be overweight,” adds Kristin Junge. One possible reason is that mother and child usually spend the first year together – a long period of time during which the baby is highly aware of the mother’s reaction to stress and the associated behavioral patterns.

“The young child obviously feels that the mother is nervous and overwhelmed,” explains Junge. Daughters are especially affected and are influenced over the long term. A possible explanation for this can be drawn from previous scientific studies. Boys may perceive psychological factors such as their mother’s reaction to stress less intensely or may be able to better compensate for it.

Interestingly, however, it was not possible to show a connection between mothers’ reactions to stress and their breastfeeding behavior in the study. What's more, stress has no significant effect on the weight development of children during pregnancy and after age two.

So what should be done to reduce the stress of mothers and to avoid exposing newborns to the risk of becoming overweight? As the evaluation of the LiNA data further showed, mothers with significantly increased stress levels are often confronted with heavy traffic or noise pollution, and they often live in quite a basic living environment, or are on a low income. Add to this a diet containing too much sugar and the children not getting enough exercise, and it can all contribute to excess weight later in life.

A look at the statistics also shows that this is a social problem in Germany. For example, almost ten percent of children in Germany between the ages of two and six are overweight, and three percent are even obese. UFZ researcher Kristin Junge therefore recommends that the stress experienced by mothers be taken seriously, especially during the first year postpartum.

“Midwives, gynecologists, and pediatricians should be particularly alert to signs of maternal stress after the birth of the child,” says Junge. In the future, researchers at the Helmholtz Centre for Environmental Research (UFZ) will investigate how mothers’ reaction to stress affects their children after the age of five.