Fluoride supplementation (with tablets, drops, lozenges or chewing gum) in pregnant women for preventing dental caries in the primary teeth of their children.

Design: randomized controlled trial (parallel-group). Participants: 1400 pregnant women in the first trimester from communities with fluoride-deficient drinking water in Southern Maine, USA.

Prenatal: sodium fluoride tablets 2.2 mg daily (1 mg fluoride ion) from the fourth month of pregnancy; control received placebo tablets during pregnancy. Postnatal: fluoride drops from birth to 2 years and one 0.5 mg fluoride tablet daily for children aged 2-3 years; provided to both groups.

Prenatal fluoride supplementation did not reduce caries in the primary teeth of offspring at 3 or 5 years. For outcomes: caries at 3 years RR 1.46 (95% CI 0.75–2.85); at 5 years RR 0.84 (95% CI 0.53–1.33). Fluorosis at 5 years showed no clear difference. Evidence quality: very low. Conclusion: There is no evidence that fluoride supplements taken by pregnant women are effective in preventing dental caries in their offspring.

Included study was at high risk of bias with substantial loss to follow-up (20% at 3 years; 38% at 5 years); only one trial; very low-quality evidence; postnatal fluoride given to both groups may confound prenatal effect.