New research published in JAMA Network Open add reassurance about the safety of community water fluoridation during pregnancy
Community water fluoridation has been a cornerstone of public health for over 75 years, helping millions of Americans maintain healthy teeth and prevent tooth decay. Yet despite decades of proven benefits, questions occasionally arise about its safety, particularly for pregnant women and their babies.
A new study published in JAMA Network Open found no evidence of an association between community water fluoridation and birth weight or other birth outcomes, providing additional reassurance for expectant parents.1
A rigorous look at birth outcomes
Researchers from Columbia University analyzed data from more than 11 million singleton births across 677 counties between 1968 and 1988, a period when community water fluoridation was introduced at different times across the country. This large-scale study took advantage of the staggered rollout of water fluoridation across the United States to compare birth outcomes in communities before and after fluoridation was implemented, using counties that never fluoridated as controls.
The study examined multiple measures of newborn health, including birth weight, low birth weight rates, gestational length, and prematurity. Birth weight is particularly important because it serves as a widely accepted indicator of infant health and has been associated with long-term health and development outcomes.
"What we found was there was no relationship between water fluoridation and birth outcomes — that when an area fluoridates, we don't see any changes in birth outcomes, either measured by birth weight or gestational length," explained lead researcher Matthew Neidell, PhD, of Columbia University.
Clear findings: no association found
The researchers found no statistically significant association between community water fluoridation and any of the birth outcomes studied.
The statistical analysis showed no meaningful change in birth weight following fluoridation. Changes in birth weight following community water fluoridation were small in magnitude, ranging from −8.44 grams to 7.20 grams. These differences represent less than 0.3% of the average birth weight and are not considered clinically meaningful.
The analysis also found no association between fluoridation and the proportion of low birthweight babies, gestational length, or risk of premature birth.
Why this study matters
What makes this research particularly valuable is its rigorous design. Unlike some previous observational studies that compared different populations, this study used an event-study difference-in-differences approach. This method compared changes in birth outcomes within the same communities over time, before and after fluoridation was introduced. This design helps address concerns about confounding factors that can make it difficult to draw clear conclusions from health research.
The in-utero period also offers a unique research opportunity. As Dr. Neidell noted, it provides a window to cleanly measure exposure to water fluoridation, since fluoride crosses the placenta and the exposure period is well-defined from conception to birth.3
Expert perspective: dispelling myths about fluoride
Dr. Nikki Zite, a professor of obstetrics and gynecology at the University of Tennessee Graduate School of Medicine in Knoxville, who was not involved in the study, emphasized its importance for public health. "This study does provide reassurance that the effective public health measure of community fluoridated drinking water does not cause poor birth outcomes," she noted. 2
Dr. Zite also highlighted the real health consequences of inadequate fluoride exposure. In her clinical practice, she sees significant dental disease in populations that rely on well water without fluoridation. "There are significant negative consequences to poor dental hygiene in pregnancy, so I had always been confused by the negativity around safe levels of fluoride being added to drinking water," she explained. "This study should be helpful to dispel the myths or fears about safe levels of fluoride being added to water."
Continued confidence in a public health success story
The Centers for Disease Control and Prevention has called water fluoridation one of the ten great public health achievements of the 20th century. Since 1945, when Grand Rapids, Michigan became the first city to fluoridate its water supply, this intervention has been associated with reductions in tooth decay of approximately 25–35% across age groups.
This study adds to a substantial body of evidence indicating that community water fluoridation, at levels used in public water systems, has not been shown to adversely affect birth outcomes.
What this means for Tennessee families
For families across Tennessee, water fluoridation remains a safe, effective, and equitable way to protect oral health. The benefits extend across the lifespan, helping children develop strong, healthy teeth and helping adults prevent cavities and maintain their smiles.
Based on this research, pregnant women can feel reassured that current evidence does not show an association between drinking fluoridated water and adverse birth outcomes.
As medical professionals emphasize, maintaining good dental health during pregnancy is important for both maternal and infant health. Alongside regular prenatal care and good oral hygiene practices, community water fluoridation continues to play a supportive role in promoting overall health for mothers and children.
Hear Tennessee dentists advocate for community water fluoridation
References:
2 https://www.medpagetoday.com/obgyn/pregnancy/119495
3 The researchers conducted multiple sensitivity analyses to test the robustness of their findings, including examining only counties with high fluoridation coverage and accounting for state-specific trends. Across all analyses, the findings were consistent: no evidence of an association between fluoridation and adverse birth outcomes.
The authors also noted limitations, including that fluoride exposure was measured at the community level rather than individually, and that other public health changes may have occurred alongside fluoridation.