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Article of the month from Dr. Christine Till and Trainees (April 2022 selection)

Article of the month from Dr. Christine Till and Trainees (April 2022 selection)

Maternal fluoride exposure, fertility and birth outcomes: The MIREC cohort

Carly Goodman, Meaghan Hall, Rivka Green, Christine Till

What do you need to know?

Fluoride can occur naturally in freshwater and is sometimes added to public water supplies for dental protection. High levels of fluoride exposure in pregnant women (more than 1.5 mg/L) have been associated with adverse pregnancy and birth outcomes. However, little is known about the effect of community water fluoridation on pregnancy and birth outcomes.

What is this research about?

The main goal of this study was to examine the relationship between maternal fluoride exposure, fertility, and birth outcomes among a group of pregnant Canadian women living with and without community water fluoridation.

What did the researchers do?

This study used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) study, which recruited pregnant women from 10 cities across Canada.  Fluoride exposure during pregnancy was measured in three ways: 1) maternal urinary fluoride concentrations averaged across trimesters (for 1566 women); 2) water fluoride concentration (for 1370 women); 3) fluoride intake based on self-reported consumption of water, tea, and coffee, adjusted for body weight (for 1192 women).

The researchers also assessed data on fertility, infant birth weight, gestational age, preterm birth (less than 37 weeks), and whether infants were small-for gestational age. They examined the relationship between fluoride exposure, fertility, and these birth outcomes.

What did the researchers find?

In this Canadian cohort, it was found that fluoride exposure during pregnancy was not associated with fertility, preterm birth, birth weight, gestational age, or infants being small for gestational age. Notably, the majority of women in this cohort were exposed to water fluoride levels lower than 0.7 mg/L, which is the standard water fluoridation level. 

The researchers note that these results are inconsistent with pre-existing studies, and that this may be due to differences in the group characteristics, research methodology, and low levels of fluoride exposure.

How can you use this research?

These findings are an important step toward better understanding the safety of fluoride exposure for pregnant women. To the researchers’ knowledge, this was the first study to examine the relationship between maternal exposure to fluoride and both birth outcomes and fertility for women living in communities with and without water fluoridation. Strengths of this study included the use of several measures of fluoride exposure, the use of a large cohort, and controlling for many confounding factors.

About the researchers:

Department of Psychology, Faculty of Health, York University, Toronto, Canada

Carly Goodman, Meaghan Hall, Rivka Green, Christine Till

Pediatrics and Environmental Health, Cincinnati Children’s Hospital Medical Center, Cincinnati, USA

Richard Hornung

School of Dentistry, Indiana University, Indianapolis, USA

Esperanza Angeles Martinez-Mier

Faculty of Health Sciences, Simon Fraser University, Burnaby, Canada

Bruce Lanphear


Goodman, C., Hall, M., Green, R., Hornung, R., Martinez-Mier, E. A., Lanphear, B., & Till, C.
       (2022). Maternal fluoride exposure, fertility and birth outcomes: The MIREC
       cohort. Environmental Advances7, 100135.

Read full article here