There's more bad news for manufacturers (and defenders) of artificial sweeteners. A study published this fall in the International Journal of Obesity reports that the consumption of diet soda or use of the noncaloric sweeteners Nutrasweet or Equal during pregnancy is associated with higher Body Mass Index (BMI) and fat mass in those children, from babyhood all the way through early adulthood. Use of zero-calorie sweeteners during pregnancy is not uncommon, by the way. About a third of pregnant women report using them on any given day.
This latest study followed about 1700 women from Massachusetts. About 70% of them were white and the average BMI before pregnancy was 24.6—just shy of what would be considered overweight. They asked the women to indicate how often they used artificial sweeteners or drank diet soda during the first two trimesters of pregnancy. Then they followed the children from birth to the age of 18, recording their BMI and body fat.
The researchers adjusted the data to account for a whole slew of things that could potentially skew the findings—including the mother's pre-pregnancy BMI, age, race/ethnicity, education, previous pregnancies, pre-pregnancy physical activity, smoking, and the dad's BMI and level of education. And after taking all that into account, they still found that kids born to moms who consumed artificial sweeteners one or more times a day during their pregnancies had higher BMIs and higher fat mass compared to kids whose moms consumed little to no artificial sweeteners. The differences grew larger as the kids got older.
All together now: Correlation is not causation
Now, if I were in charge of public relations for artificial sweeteners—which I'm not—I would point out that this is merely a correlation and does not prove that artificial sweeteners had anything to do with these kids' weight or body composition. Although they collected a lot of information about the parents and used that to adjust their analysis, the researchers collected virtually no information about the diet or lifestyle of the kids over the subsequent 18 years. You could argue that what the kids ate and how much physical activity they got throughout their lifetime had a lot more to do with their body weight than whether their moms drank diet soda while pregnant. And you wouldn't be wrong.
Are kids whose moms drink diet soda more likely to drink diet soda themselves? I can't find any data to support that (which doesn't mean that it doesn't exist), but it seems likely. For sure, kids are consuming more artificial sweeteners than they used to. About 25% of kids report consuming them on a daily basis. And the proliferation of low- and no-sugar products in the marketplace may be an additional source of these sweeteners that neither kids nor parents are even aware of.