Aspartame in Pregnancy: Diet Soda Linked to Tripled Autism Risk in Boys

When Sarah reached for her third Diet Coke of the day during her pregnancy, she thought she was making the healthier choice—avoiding sugar and extra calories. But recent research suggests this seemingly innocent swap may come with considerations expecting parents should know about.

We’ve all been there: craving something sweet but trying to avoid the guilt of regular soda. The artificial sweetener aspartame has been our go-to solution for decades—promising all the taste with none of the calories.

But a notable 2023 study in Nutrients titled “Daily Early‑Life Exposures to Diet Soda and Aspartame Are Associated with Autism in Males: A Case‑Control Study” (PMID: 37686804) found that expecting mothers who consumed daily diet soda or equivalent aspartame (≥177 mg/day) during pregnancy or breastfeeding had over three times the odds of having a son diagnosed with autism—specifically non‑regressive autism.

Source: https://pubmed.ncbi.nlm.nih.gov/37686804/

Real People, Real Experiences

“My husband was habitually drinking flavored seltzer sweetened with aspartame when he became anxious, irritable, and developed insomnia. As soon as he stopped consuming it, the adverse effects dissipated.” — Reddit user

Though anecdotal, such stories reflect how individuals perceive aspartame’s effects—subtle signs not captured in scientific studies but worth noticing.

Additional Research Highlights

• Kidney development (rats): A 2021 rat study (PMID: 33128303) found that maternal consumption of aspartame—alone or with caffeine—delayed kidney development in offspring.

Source: https://pubmed.ncbi.nlm.nih.gov/33128303/

• Placental dysfunction and birth weight: A 2024 study (PMID: 39547074) involving rats and a small human cohort showed maternal aspartame intake impaired placental function and was linked to lower birth weight.

Source: https://pubmed.ncbi.nlm.nih.gov/39547074/

• Heritable learning & memory deficits (mice): A 2023 mouse study (PMID: 37652922) found that even moderate daily intake of aspartame (~2–4 diet sodas) caused learning and memory deficits passed down through the paternal line.

Source: https://pubmed.ncbi.nlm.nih.gov/37652922/

Understanding the Context

These findings demonstrate associations—not direct causation—yet they collectively hint at potential developmental risks tied to aspartame exposure during critical life stages.

• The autism study found a gender-specific association, affecting boys only.

• Some animal studies used higher-than-typical doses, but others mirrored common human consumption patterns.

• FDA guidelines currently consider aspartame safe during pregnancy, but emerging research may prompt some families to reevaluate intake.

Making Informed Choices

If you’re pregnant or planning to conceive, it may be worth reducing aspartame intake—especially from multiple sources like diet sodas, sugar-free gum, protein bars, and flavored water. Safer alternatives include:

• Sparkling water with real fruit juice

• Herbal teas (hot or iced)

• Water infused with fruits and herbs

• Occasional use of natural sweeteners like stevia

As always, talk with your healthcare provider when making dietary changes during pregnancy.

The Bottom Line

• A 2023 study found a 3x increased risk of autism in boys whose mothers consumed diet soda/aspartame daily during pregnancy.

• Animal studies suggest potential risks to kidney development, placental function, and cognitive health across generations.

• While not conclusive, these studies offer strong reasons to approach aspartame with informed caution during pregnancy.

Further Reading

• Aspartame & Autism Risk: Nutrients 2023 – https://pubmed.ncbi.nlm.nih.gov/37686804/

• Kidney Effects: Birth Defects Res 2021 – https://pubmed.ncbi.nlm.nih.gov/33128303/

• Placental Function: Placenta 2024 – https://pubmed.ncbi.nlm.nih.gov/39547074/

• Cognitive Deficits (Heritable): Sci Rep 2023 – https://pubmed.ncbi.nlm.nih.gov/37652922/