Maternal smoking during pregnancy affects gut bacteria in infants, which can lead to obesity

A recent study published in the journal Gut Microbes has provided another reason for women to avoid smoking during pregnancy. The research found an association between mothers smoking during pregnancy and a higher risk of their children becoming overweight or obese.

Childhood obesity is a growing global concern, affecting more than 18 percent of children and adolescents aged five to 19 in 2020, a significant rise from just four percent in 1975. This issue is linked to negative outcomes such as poorer health, lower self-esteem, and a higher likelihood of being bullied.

Anita Kozyrskyj

Anita Kozyrskyj

Anita Kozyrskyj, a microbiome epidemiologist and professor of pediatrics at the University of Alberta, co-authored the study. Kozyrskyj, a member of the Women and Children’s Health Research Institute, has extensively researched early life factors affecting infant gut bacteria, including birth methods, feeding practices, maternal health, and pregnancy stress.

maternal smoking obesity pregnancy

Photo supplied by Brooke Cagle

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Kozyrskyj noted that previous research showed a tendency for children of smoking mothers to become overweight. However, her team’s study breaks new ground by suggesting a potential reason for this association, and it is found in the gut microbes.

“We’ve known that for a long time. We just didn’t know how it happened,” Kozyrskyj said. “There may be many ways, but in our study, we showed one way is by changing the gut bacteria in the infant.”

Using data from over 1,500 children from the Canadian Healthy Infants Longitudinal Development (CHILD) Cohort, the researchers collected information on maternal environmental and lifestyle factors during pregnancy and the children’s data from birth to age three. Weight outcomes were measured at one and three years of age, and stool samples collected at three and 12 months were analyzed for bacterial profiles.

The study found that the risk of children being overweight or obese was linked to the amount and diversity of Firmicutes bacteria. Firmicutes are a group of bacteria found in many environments, including our gut. They help with digestion, absorbing nutrients, and keeping our gut healthy. They produce substances like butyrate that provide energy to gut cells and reduce inflammation. However, having too many Firmicutes can be linked to health problems including obesity and metabolic disorders.

Maternal smoking during pregnancy significantly increased the abundance of Firmicutes in the gut.

Kozyrskyj clarified that while Firmicutes are a normal part of gut bacteria, higher levels of these bacteria were found in the guts of infants whose mothers smoked during pregnancy compared to those whose mothers did not. The elevated levels of Firmicutes could lead to excessive production of butyrate, a short-chain fatty acid, which, although not toxic, was present in higher and earlier amounts among infants of smoking mothers.

The study indicates an association rather than a direct cause and effect between high butyrate levels and childhood overweight. Interestingly, this association persisted even if mothers reduced or quit smoking during pregnancy, but not if they quit before becoming pregnant. Exclusive breastfeeding for the first three months appeared to mitigate the smoking effect.

| Staff

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