Water fluoridation did not affect birth outcomes
Adding fluoride to community water was not linked to lower birthweight or other adverse newborn outcomes.
*Retrospective cohort with natural experiment; Level 2b (OCEBM).

Citation

Krebs B, Simon L, Schwandt H, Burn S, Neidell M. Community Water Fluoridation and Birth Outcomes. JAMA Network Open. 2026;9(1):e2554686. doi:10.1001/jamanetworkopen.2025.54686

Background

Community water fluoridation is widely used to prevent tooth decay, but some have raised concerns that fluoride exposure during pregnancy could harm fetal growth. Birthweight is a well-measured marker of newborn health and is linked to later health.

Patients

11,479,922 singleton births from 677 US counties (1968–1988). Excluded: multiple births and births missing birthweight or county.

Intervention

County adoption of community water fluoridation (varying coverage within counties).

Control

Counties that never adopted fluoridation or had not yet adopted it during the same time period.

Outcome

Mean birthweight (primary); low birthweight, pregnancy length, and preterm birth (secondary).

Follow-up Period

Birth outcomes measured at delivery; births tracked across 1968–1988.

Results

Fluoridation adoption was not associated with meaningful changes in birth outcomes. Mean birthweight did not change after fluoridation compared with control counties (estimated change −0.53 g; 95% confidence interval −4.75 to 3.70). Across multiple post-adoption time windows, estimated birthweight changes were small (roughly −8 g to +7 g). No significant associations were found for low birthweight, pregnancy length, or preterm birth. Sensitivity analyses (including models allowing different time patterns by state and restricting to counties with very high fluoridation coverage) supported the main findings.

Limitations

Fluoride exposure was measured at the county level rather than for each individual, which can misclassify true exposure. The study is observational, so unmeasured changes occurring alongside fluoridation (such as other water treatment changes) cannot be fully excluded. Even so, any plausible birthweight effect within the reported ranges would be clinically very small.

Funding

Swiss National Science Foundation; US National Institute on Aging.

Clinical Application

Reassure pregnant patients that community water fluoridation does not appear to worsen birth outcomes; this supports continuing standard fluoridation policies.