Is fluoride safe during pregnancy?

What does the evidence say about fluoride in drinking water during pregnancy?

1. US water systems target a fluoride level of 0.7 mg/L, the concentration public health guidance considers the right balance for supporting dental health, and federal monitoring found only about 0.01 percent of water-system months exceeded the EPA's 2.0 mg/L safety ceiling. 1
2. Fluoride crosses the placenta, and fetal cord blood fluoride levels track a pregnant person's own blood fluoride level, which is the basic mechanism behind every study asking whether maternal fluoride exposure could affect a developing fetus. 2
3. A 2024 study of 229 mother-child pairs in a fluoridated part of Los Angeles found that higher maternal urinary fluoride during pregnancy, at levels the authors describe as typical of fluoridated communities in North America, was associated with roughly double the odds of a child showing clinical-range behavioral problems at age 3. 3
4. A separate 2024 study following 357 young adults in Australia found no meaningful IQ difference between people with full lifetime exposure to fluoridated water and people with none, with the small gap that did appear falling within a range researchers consider equivalent to no effect. 4
5. An earlier, widely cited analysis linking fluoride to lower childhood IQ pooled studies from regions with naturally high fluoride, some over 10 mg/L; its own authors said the findings couldn't be used to set an exposure limit and didn't address the much lower 0.7 to 1.2 mg/L levels used in US water fluoridation. 5

Is fluoride in drinking water safe in each trimester?

• First trimester. The research linking prenatal fluoride exposure to child outcomes measured fluoride across pregnancy rather than isolating the first trimester specifically, so there's no evidence pointing to this window as more or less sensitive than the rest of pregnancy. This is a reasonable time to mention any concerns to your prenatal provider if you're weighing whether to change your water source.
• Second trimester. The same picture continues: the 2024 study that found a possible link didn't break its results out by trimester, so there's nothing second-trimester-specific to flag beyond the general question of how much fluoridated tap water you're drinking day to day.
• Third trimester. No trimester-specific data exists here either. If you'd rather reduce your fluoride intake for the rest of pregnancy, reverse osmosis and activated alumina filters are established methods for removing it from water, an option worth knowing about even though public health guidance still supports community water fluoridation.