Is aspartame safe during pregnancy?

What does the evidence say about aspartame during pregnancy?

1. The FDA considers aspartame safe for most people at its acceptable daily intake of 50 mg per kilogram of body weight per day. 1
2. People with phenylketonuria (PKU), a rare inherited disorder, need to avoid or limit aspartame, which is why federal law requires a phenylalanine warning on any product that contains it. 1
3. Every newborn is screened for PKU with a routine heel-prick test, and the real pregnancy risk comes from a mother's own unmanaged PKU, not from ordinary aspartame use by someone without the condition. 2
4. In 2023, a WHO cancer research group labeled aspartame a possible carcinogen, but the FDA disagreed, and the separate WHO/FAO group that sets safe intake levels left its daily limit unchanged. 1
5. One large study of nearly 60,000 Danish pregnant women linked daily diet soda to a higher chance of preterm delivery, but the researchers said more research was needed, and no health agency has changed its guidance because of it. 3

Is aspartame safe in each trimester?

• First trimester. Aspartame's safety doesn't change by trimester: the FDA's daily limit is a lifetime measure, so normal use early in pregnancy is judged the same as at any other time. The one real exception, PKU, is something you'd already know about from newborn screening, not something new that shows up during pregnancy.
• Second trimester. No new caution applies in the second trimester. Even if nausea eases and you're drinking more diet soda or chewing more sugar-free gum, normal use still stays well within the safe intake level set by the FDA and international reviewers.
• Third trimester. The 2023 cancer hazard debate hasn't changed guidance for the third trimester or any other stage of pregnancy: the WHO/FAO group that sets safe intake levels reviewed the same data and left its daily limit unchanged. Bring any product questions to a prenatal visit rather than cutting out aspartame just to be safe.