Key clinical point: Maternal fluoride exposure during pregnancy was associated with a decrease in IQ score in children at 3 years and 4 years.

Major finding: After adjustment for covariates, there was a significant interaction between MUF_SG and the child gender (P = .02), and a 1-mg/L MUF_SG increase was associated with a decrease in 4.49 IQ points in boys (95% confidence interval, −8.38 to −0.60) but not girls. There was also an association between 1-mg higher daily intake of maternal fluoride intake and decreased IQ score in both boys and girls (−3.66; 95% CI, −7.16 to −0.15).

Study details: A prospective, multicenter birth cohort study of fluoride exposure during pregnancy in 512 mother-child pairs in six Canadian cities.

Disclosures: This study was funded in a grant from the National Institute of Environmental Health Science, and the MIREC Study was funded by Chemicals Management Plan at Health Canada, the Ontario Ministry of the Environment, and the Canadian Institutes for Health Research. Dr. Bruce Lanphear reported being an unpaid expert witness for an upcoming case involving the U.S. Environmental Protection Agency and water fluoridation. Dr. Richard Hornung reported receiving personal fees from York University. Dr. E. Angeles Martinez-Mier reported receiving grants from the National Institutes of Health. The other authors report no conflicts of interest. Dr. Bellinger reported no conflicts of interest with regard to his editorial.