Research, published this week in JAMA Pediatrics, demonstrates a link between the consumption of artificially sweetened drinks during pregnancy and an increase in the body mass index of their infants. Although the results of the study cannot prove causation, they are sure to spark further research.

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New research investigates the effects artificial sweeteners on the unborn child.

Today, the Western world is in the midst of an obesity crisis, and this includes our young. Obesity has doubled in children and quadrupled in adolescents over the last 3 decades.

Sugar added to foods and drinks is known to play a significant part in this epidemic.

Because of this, replacing sugary drinks with artificially sweetened options seems like a safer bet. After all, the calories they add to the products are negligible, or nonexistent.

As of 2012, almost one quarter of American adults consume drinks containing non-nutritive sweeteners (NNSs) on a daily basis.

These replacements are relatively new ingredients and, as such, their effects are not well charted.

There is a small body of evidence suggesting that NNSs might increase the risk of metabolic disease and obesity in adults. There is also evidence from animal models that suggests NNSs consumed during pregnancy might produce obesity and metabolic problems in the infant.

However, the consumption of NNSs during pregnancy and the consequences for the developing child have not previously been studied in humans.

Researchers from the University of Manitoba, Winnipeg, Canada, led by Meghan B. Azad, Ph.D., set out to look at the role of NNSs and the unborn child in more detail.

Using a questionnaire, the investigators examined 3,033 mothers and infants. They searched for connections between the consumption of artificially sweetened drinks during pregnancy and the future body mass index (BMI) of the child.

Assessing whether the weight of a child is “normal” is more challenging than it is for adults. In the study, the team used the BMI z-score. This measure compares a child’s weight with a large number of other children and takes age and sex into consideration, as well as their pattern of growth.

The BMI z-score indicates how a child’s weight compares with the average BMI for their age and sex. As an example, a BMI z-score of 2.5 means that the child is 2.5 standard deviations above the average value.

In the current study, the average age of the mothers was 32.4 years; the average BMI z-score was 0.19 at 12 months old, and 5.1 percent were overweight. Of the mothers, 29.5 percent drank artificially sweetened drinks during pregnancy, and 5.1 percent drank artificially sweetened drinks on a daily basis.

The researchers found that, compared with women who drank no artificially sweetened drinks, consuming them daily was associated with an increase in BMI-z of 0.2, and the risk of an infant being overweight by the age of 1 year doubled.

These results remained significant when other relevant factors were taken into account, including the mother’s BMI, quality of diet, and total energy intake.

To our knowledge, our results provide the first human evidence that artificial sweetener consumption during pregnancy may increase the risk of early childhood overweight.

Given the current epidemic of childhood obesity and the widespread consumption of artificial sweeteners, further research is warranted to replicate our findings in other cohorts, evaluate specific NNS and longer-term outcomes, and study the underlying biological mechanisms.”

Meghan B. Azad, Ph.D.

Although the study cannot prove causation, and there are inherent problems with self-reported dietary information, the results certainly are worth further investigation, especially when taken in conjunction with existing animal and adult studies.

Because research data is relatively few and far between, the exact pathways that lead from NNS consumption to metabolic issues are not understood. An editorial that accompanies the JAMA Pediatrics research paper briefly outlines some of the possible mechanisms.

Some theorize that when mouth and gut receptors encounter NNSs they stimulate appetite, which then leads to weight gain over time. Some believe that the artificial sweeteners might alter the types or numbers of bacteria in the gut and create metabolic changes. These theories can not easily account for the potential changes in fetal metabolism, though.

Whatever mechanisms are at play, this area of nutrition science deserves more study. Already, thousands of food and drink products contain NNSs, and for this reason alone, research into their health implications is vital.

Learn more about childhood obesity.