Smoking while pregnant linked to changes in baby’s microbiome, increased risk of obesity
CHILD research has found that if a mother smokes while pregnant, this affects the bacteria living in her baby’s gut and puts the baby at higher risk of becoming overweight or obese in early childhood.
The research also found that exclusive breastfeeding for the baby’s first 3 months of life may lower this risk, while quitting smoking when already pregnant does not.
HIGHER BMI AT AGE 3
The research, published in Gut Microbes, looked at microbiome data from 1,592 kids participating in the CHILD Cohort Study (CHILD). The microbiome is the community of beneficial bacteria cohabiting with our bodies, especially in our digestive system or gut. Scientists are coming to appreciate more and more the role of the microbiome in our health.
Information about the microbiome of these CHILD participants came from analyzing their stool samples, or poop, collected from them at 3 and 12 months of age, which revealed which bacteria were living in their gut.
As well as microbiome information, the researchers looked at weight and height when the children got older, as measured by CHILD staff at clinical visits when they were 1 and 3 years old. The researchers knew about the moms’ smoking habits from questionnaires completed by the moms when pregnant and afterwards.
“Among the Study participants we looked at, kids whose moms continued smoking through pregnancy, even at a reduced rate, tended to have the highest BMI (body mass index) scores by age 3, which is to say they were typically the most overweight,” comments the senior author, CHILD researcher Dr. Anita Kozyrskyj of the University of Alberta.
“Even those kids whose moms quit smoking during pregnancy were at higher risk of obesity compared to kids whose moms never smoked or quit before becoming pregnant. What’s more, BMI scores were impacted more by their moms’ smoking during pregnancy than by their later exposure to second-hand smoke after birth,” she adds.
“As a side note, the chidren of smoking moms also tended to have high levels of markers in their urine, in the form of metabolites, indicating their exposure to nicotine.”
SOMETHING’S GOING ON IN THE GUT
The researchers found an association between the kids’ increased risk of being overweight and a couple of changes in their microbiome: When mom smoked during pregnancy, a kind of bacteria known as Firmicutes in the kids’ guts increased too fast and too soon. This, in turn, led to the overproduction of butyrate, a short chain fatty acid. This combination of changes coincided with an increased risk of obesity.
“Feeding the babies nothing but breastmilk—exclusive breastfeeding—for the first 3 months of life also influenced the kids’ weight later on,” observes lead author Dr. Hein M. Tun. “Among kids with smoking moms, those who were exclusively breastfed had a lower BMI. This was also true among the children of non-smoking moms.”
“Which makes sense,” notes Dr. Kozyrskyj, “given we already know from other research how important breastfeeding is to the development of a healthy microbiome.”
The authors note that these findings add supporting evidence on the benefits of women quitting smoking before becoming pregnant, including lower nicotine metabolite levels in their babies.
“These findings may also help us develop new ways of promoting healthy weight in young children, perhaps by influencing their microbiomes with products like probiotics,” adds Dr. Tun.
