Fluoride exposure in pregnancy can affect offspring’s IQ

• Marian Freedman
• Jon Matthew Farber, MD

A study in 512 mother-child pairs from 6 major cities in Canada found that exposure to higher levels of fluoride during pregnancy was associated with lowered intelligent quotient (IQ) scores in their children at the age of 3 to 4 years.

About 41% of participants lived in communities supplied with fluoridated municipal water. Investigators matched participants’ postal codes with water treatment plan zones to estimate water fluoride concentration for each woman. Using a questionnaire, they determined mothers’ consumption of tap water, coffee, and tea during the first and third trimesters and measured maternal urinary fluoride (MUF) concentration in each trimester of pregnancy. They assessed children’s IQ when they were aged 3 or 4 years, using standardized tests.

As expected, median MUF concentration was significantly higher among women who lived in communities with fluoridated drinking water, as was their daily estimated fluoride intake, compared with those who did not live in such communities. Analyses showed that an estimated 1-mg increase in maternal fluoride intake was associated with a 3.66 lower IQ score among both boys and girls. A 1-mg/L increase in MUF was associated with a 4.49-point lower IQ score in boys but not in girls (Green R, et al. JAMA Pediatr. 2019;173[10]:940-948).

Thoughts from Dr. Farber

I do not like giving anti-fluoride spouters ammunition, but I have to follow science where it leads. The reviewers and editors were very brave to publish this controversial study. We will see if it is replicated down the road. The study looked only at pregnant women, so continue to give fluoride, a well-proven treatment, to your pediatric patients who need it.