An observational study of 601 mother-child pairs from six cities in Canada hints at an apparent association between maternal exposure to fluoride during pregnancy and lower IQ scores measured in children ages 3 to 4.
More than a third of Canadian residents are supplied with fluoridated water. In the United States, most residents are supplied with fluoridated water, while only 3% of European residents are supplied. The study analyzed two measures of fluoride exposure during pregnancy.
Data in maternal urinary fluoride concentrations and children’s IQ were available for 512 mother-child pairs, and self-reported consumption of tap water and other water-based drinks such as tea and coffee and IQ scores were available for 400 of the 601 mother-child pairs.
After accounting for factors associated with fluoride metabolism and children’s intellectual abilities, a 1-mg/L increase in maternal urinary fluoride was associated with a 4.5-point lower IQ score in boys without a statistically significant association with IQ score in girls. A 1-mg higher intake of fluoride was associated with a 3.7-point lower IQ score among boys and girls.
The researchers note that their conclusions are limited by the study’s observational design, which can’t account for unmeasured factors that could explain the results. Also, there was no assessment of children’s fluoride exposure during infancy.
The study, “Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada,” was published by JAMA Pediatrics.