Scientific Article Review: Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

Published In: JAMA Pediatrics
Publication Year: 2019

Study Design

This research was a prospective multicenter birth cohort study based on data from the Maternal-Infant Research on Environmental Chemicals (MIREC) program, involving 601 mother-child pairs from six major cities in Canada.

Funding Sources

The study received funding from:

• The National Institute of Environmental Health Sciences (grant R21ES027044)
• Health Canada’s Chemicals Management Plan
• The Ontario Ministry of the Environment
• The Canadian Institutes for Health Research (grant MOP-81285).

PICO Framework - what was studied and how?

Population: Pregnant women from Canada and their children, tested at 3–4 years of age.

Intervention: Maternal fluoride exposure measured through urinary fluoride (MUFSG) and self-reported daily fluoride intake during pregnancy.

Comparison: Pregnant women exposed to non-fluoridated versus fluoridated water.

Outcomes: Children’s IQ scores (Full Scale IQ, Verbal IQ, and Performance IQ).

In Paragraph Form:
The study explored the association between maternal fluoride exposure during pregnancy and the cognitive abilities of children, as assessed by IQ tests at 3–4 years old. Researchers examined fluoride exposure in women living in fluoridated and non-fluoridated communities and evaluated its potential effects on children’s cognitive outcomes.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Pregnant women within 14 weeks of gestation.
• Women capable of communicating in English or French.

Exclusion Criteria:

• Pregnancies with known fetal abnormalities.
• Medical complications during pregnancy.
• Maternal illicit drug use during pregnancy.

Demographics and Study Design

• Total participants: 512 mother-child pairs (for MUFSG analysis).

  • Fluoridated water group: 141 mothers.
  • Non-fluoridated water group: 228 mothers.

• Mean maternal age at enrollment: 32.3 years.

• Children’s mean age at testing: 3.42 years.

• Child sex distribution: 52% female.

• Ethnicity: 90% of mothers identified as white.

Primary Outcome Variables and Results

Outcome: Children’s Full Scale IQ (FSIQ).

• Boys: A 1 mg/L increase in maternal urinary fluoride was associated with a 4.49-point reduction in IQ (95% CI: -8.38 to -0.60, p = 0.02).
• Girls: No significant association observed.
• Combined daily maternal fluoride intake across boys and girls showed a reduction of 3.66 IQ points per 1 mg increase (95% CI: -7.16 to -0.14, p = 0.04).

Conclusions

Maternal fluoride exposure during pregnancy was associated with lower IQ scores in offspring, particularly in boys. These findings raise concerns about the cognitive risks of prenatal fluoride exposure, even in communities with fluoridation levels considered optimal.

Discussion

Strengths:

• Robust data collection with measures of fluoride exposure across all pregnancy trimesters.
• A large sample size for a cohort study of this nature.

Limitations:

• Reliance on self-reported fluoride intake, which could introduce recall bias.
• Lack of maternal IQ data to account for genetic or environmental confounders.
• Variability in fluoride measurements across municipal water systems.

Citation

Green R, et al. Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada. JAMA Pediatr. 2019;173(10):940-948. https://pubmed.ncbi.nlm.nih.gov/31429830

Visual Aids

Simple Chart: Fluoride Exposure and IQ Reduction