AUSTIN (KXAN) – A team of researchers say they have observed a link between autism diagnosis in boys and their mothers drinking at least one diet soda daily or consuming an equivalent amount of the sweetener aspartame during pregnancy or while breastfeeding, according to a new study.

In the study, the researchers at the University of Texas Health Science Center at San Antonio asked the parents of 235 children with an autism spectrum disorder and 121 children without autism, who were the study’s controls, to complete a retrospective questionnaire about their diet soda and aspartame intake while pregnant or breastfeeding their children.

Researchers asked biological mothers, “While you were pregnant or breastfeeding your child, how often did you drink diet drinks containing artificial sweeteners? Please count diet sodas first, such as Diet Coke, Diet Dr. Pepper, and Diet Sprite, and then other diet drinks, such as Crystal Light, sugar-free Kool-Aid, Slim-Fast, and other ‘lite’ drinks.”

Note that not all diet beverages contain aspartame. The researchers did not ask women to only think about aspartame-containing diet beverages they consumed while pregnant or breastfeeding. However, all drinks listed in the survey’s examples do contain aspartame.

The team found that boys with autism had more than three times the likelihood of having a mother who drank diet soda daily while pregnant or breastfeeding than boys without autism, per the findings, published in the peer-reviewed journal Nutrients.

The researchers did not find a statistically significant association with girls. 

“These associations do not prove causality but taken in concert with reports from earlier studies of increased prematurity and cardiometabolic health impacts among infants and children exposed daily to diet beverages [or] aspartame during pregnancy, our findings raise new questions about potential neurological impacts that need to be addressed,” Raymond F. Palmer, author of the paper and professor in the Department of Family and Community Medicine at UT Health San Antonio, said in a news release.

The study authors wrote that further research, including efforts with larger sample sizes, should be conducted to continue to explore the link between aspartame and developing autism.

Still, they conclude that mothers might exercise caution while pregnant or breastfeeding when drinking diet sodas or consuming products with a commensurate amount of aspartame. 

These study results follow a June announcement from the World Health Organization when they deemed aspartame a “possible” cause of cancer. Still, WHO officials said they were not directing consumers to completely cut out the sugar alternative but to practice moderation with products. 

Following the WHO announcement, the U.S. Food and Drug Administration, which approved some consumption of aspartame in 1974, clarified that just because the substance is “possibly carcinogenic” does not mean it is linked to cancer.