THURSDAY, Jan. 22, 2026 (HealthDay News) -- Community water fluoridation (CWF) is not associated with adverse birth outcomes, according to a study published online Jan. 20 in JAMA Network Open.
Benjamin Krebs, Ph.D., from the University of Basel in Switzerland, and colleagues conducted a cohort study to examine the association between prenatal exposure to CWF and birth outcomes using an event-study analysis with a difference-in-differences approach, exploiting the staggered rollout of CWF from January 1968 to December 1988 across U.S. counties.
The sample included 11,479,922 singleton births across 677 counties (408 CWF-treated [60.3 percent] and 269 never treated [39.7 percent]) during the 21-year period. The researchers found no evidence of an association for CWF with birth weight or other birth outcomes. No discernible pretreatment trends were seen, and there were no significant changes after adoption of CWF, with estimates of small magnitude seen across all posttreatment periods, ranging from −8.44 to 7.20 g. Sensitivity analyses incorporating state-specific time trends, alternative exposure thresholds, and tests for compositional changes in births supported these findings.
"CWF is not associated with infant health as measured by birth weight, contributing to ongoing evaluations of the safety of CWF, particularly with regard to potential adverse effects during pregnancy," the authors write.