But little research has been done on pregnant women consuming such drinks and the impact it may have on their children. Now, a new report published in JAMA Pediatrics suggests that when women drink artificially sweetened beverages on a daily basis during pregnancy, their children are twice as likely to be overweight as infants.
For the study, Meghan B. Azad, Ph.D., of the University of Manitoba in Winnipeg, Canada and her colleagues examined over 3,000 mother-infant pairs. They asked the women to fill out a food questionnaire during pregnancy, including questions on how often they drank artificially sweetened beverages, such as diet soda and tea or coffee with artificial sweetener added, and sugar-sweetened drinks, such as regular soda or coffee or tea with sugar or honey. The researchers followed up by measuring infant body mass index (BMI) when the children were a year old.
An analysis of the data showed that daily consumption of artificially sweetened beverages was associated with a two-fold increase in the risk of an infant being overweight at 1 year of age.
The researchers controlled for a number of other factors that could have influenced the children's weight, including maternal obesity, diabetes, and general diet quality.
No association was seen with sugar-sweetened beverages. This finding surprised the researchers somewhat, but Azad notes that this in no way means sugary drinks are a better choice.
"We didn't find an independent association with the sugar-sweetened beverages but we did find an association with total calorie consumption," she explained. "Before correcting for total calories, we did see a pattern where more sugar-sweetened beverages were associated with a higher risk of overweight in the infants. So, sugar sweetened beverages do appear to have an impact, but this is explained by the calories they contain."
The results suggest then that there may be something about the artificially sweetened beverages specifically -- such as certain chemicals or additives used -- that might result in infant weight gain. While the study did not look at potential mechanisms behind the results, Azad has some theories.
"There is some evidence that consuming artificial sweeteners at least in adults changes the microbiome," she said. "We know that our gut bacteria are important for a variety of health issues, including our metabolism. Bacteria help us digest the food we eat and they play a role in how much calories we extract from that food. And so if these artificial sweeteners are changing the mom's microbiome, which then gets passed on to the baby, that might be one mechanism."
Another possibility is that artificial sweeteners disrupt metabolism in a different way.
"Our bodies have evolved to respond to sugar in a certain way, and some of these responses are triggered by the perception of sweet taste," she said. "With artificial sweeteners, we get the perception of sweet taste without any actual sugar to metabolize. There's some evidence in adults that routinely consuming artificial sweeteners may disrupt or 'reprogram' our metabolism, leaving us more at risk for obesity and related complications."
This might in turn be happening in infants of moms who consumed high levels of artificial sweeteners during pregnancy.
The authors note that the study is limited in several important ways, including that it only shows an association and does not prove a cause-and-effect relationship. There is also the possibility that the participants may have misreported how often they drank sweet beverages.
In an accompanying editorial, Mark A. Pereira, Ph.D., of the University of Minnesota, and Matthew W. Gillman, MD, of Harvard Medical School, caution that the study is still preliminary. "Any microbiome-related mechanism is speculative," they write, "and other mechanisms, which would need to account for how maternal consumption of ASBs [artificially sweetened beverages] is transduced into an obesogenic tendency in the fetus, are not apparent."
Yet, despite the limitations, they say the findings warrant further study.
Furthermore, they write, the results "remind us that [artificially sweetened beverages] yield uncertain benefits for the mother and raise the prospect of risk for her child. Until more safety data are available, pregnant women should consider (safe) water for proper hydration and as the beverage of choice."