Is saccharin safe during pregnancy?

What does the evidence say about saccharin during pregnancy?

1. Saccharin has an acceptable daily intake of 15 mg per kilogram of body weight per day, roughly 45 tabletop packets for a 132 pound adult, and it is 200 to 700 times sweeter than table sugar with no calories. 1
2. The 1970s link between saccharin and bladder cancer in laboratory rats did not hold up in people: more than 30 human studies showed the rat results were irrelevant to humans, the National Toxicology Program concluded in 2000 that saccharin should come off the list of potential carcinogens, and the warning label is no longer required. 1
3. Saccharin crossed the placenta in every participant tested and was present in both fetal circulation and amniotic fluid, at mean concentrations of about 61 ng/mL in cord blood and 61 ng/mL in amniotic fluid. 2
4. Rats given 0.1 percent saccharin in drinking water throughout gestation produced offspring with impaired glucose handling and insulin sensitivity in both sexes, which the authors framed as a concern about critical developmental windows rather than a demonstrated human effect. 3
5. Across 17 studies and 306,147 participants, low-calorie sweetener use in pregnancy showed no association with birth weight overall, with only a small imprecise increase at frequent daily intake, and the authors rated the overall quality of that evidence as low. 4

Is saccharin safe in each trimester?

• First trimester. The cancer question people remember is settled and settled in saccharin's favor: more than 30 human studies showed the 1970s rat findings did not apply to people, and the National Toxicology Program removed saccharin from its list of potential carcinogens in 2000. The warning label came off with it.
• Second trimester. What is less settled is fetal exposure. Saccharin was detected in fetal circulation and amniotic fluid in every participant in one delivery study, at mean cord-blood levels around 61 ng/mL. Crossing the placenta is not the same as causing harm, but it does explain why obstetric caution has persisted.
• Third trimester. Saccharin is among the older sweeteners and has largely been displaced by sucralose and stevia in newer products. If you are still using it out of habit, late pregnancy is a fine time to ask your clinician whether a switch or simply less sweetener overall makes sense for you.