Is it safe to use artificial sweeteners during pregnancy?

Expert Answers
Kristina Kahl, genetic counselor

Aspartame, the artificial sweetener found in NutraSweet, Equal, and most diet soft drinks and other sugar-free treats, is considered safe for most pregnant women when consumed in moderate amounts. Saccharin, on the other hand, is more controversial.

Aspartame is composed of two amino acids, phenylalanine and aspartic acid (amino acids are the building blocks of proteins). When digested by the body, methanol, a type of alcohol is also created. Aspartame has not been shown to cause birth defects, and although some members of the public and a few scientists have raised concerns about its safety, most physicians and scientists believe that it's safe when used in moderation during pregnancy.

When it comes to aspartame, the main concern is with moms-to-be who have a genetic disease called phenylketonuria, or PKU, which prevents them from breaking down the phenylalanine in their diet. If they don't follow a specific diet, the phenylalanine builds up in their bodies, causing their babies to be mentally retarded. Fortunately, thanks to FDA-mandated labeling of products containing aspartame, avoiding it is relatively easy for expectant moms with PKU.

According to a 1985 report from the American Academy of Pediatrics Committee on Nutrition, "Present levels of aspartame consumption appear to be safe for those who do not have PKU. ...The blood phenylalanine levels reported in response to loading doses of aspartame in normal adults ... do not seem sufficiently high to warrant concern of toxicity to the individual or even to a fetus during pregnancy."

Saccharin, one of the first artificial sweeteners, is much less commonly used today. Although it hasn't been shown to cause birth defects, animal studies show that it may increase the risk of bladder cancer. When a mom-to-be ingests saccharin, it crosses the placenta into her baby's bloodstream. Research on monkeys shows that saccharin is cleared out of the baby's body more slowly than the mother's. So if an expectant mother ingests a great deal of saccharin, it could accumulate in her baby's bladder and potentially increase the baby's risk for bladder cancer. Because of this concern, some physicians ban saccharin from their pregnant patients' diets. However, if you inadvertently used saccharin before knowing you were pregnant, try not to worry. The risks, if any, of consuming a small amount in the first weeks are extremely small.

The main health issue for pregnant women who use artificial sweeteners is that they may be missing out on more nutritious foods and beverages. If you drink a lot of diet soda, for instance, you may not be getting enough water, milk, or juice, all of which are beneficial to your developing baby.