Data sourcesCochrane Oral Healths Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) Medline, Embase, LILACS BIREME Virtual Health Library CINAHL US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform databases.Study selectionRandomised controlled trials (RCTs) including quasi-randomised and cluster-randomised trials of fluoride supplements (tablets, drops, lozenges or chewing gum) given to women during pregnancy with the aim of preventing caries in the primary teeth of their children were selected.Data extraction and synthesisTwo reviewers independently extracted data and assessed risk of bias using the Cochrane risk of bias tool. No data synthesis was possible.ResultsOnly one RCT met the inclusion criteria. There was no statistical difference in decayed or filled primary tooth surfaces (dfs) or % of children with caries at three years or five years. Risk ratio (RR) at three years = 1.46, (95% CI; 0.75 to 2.85) and RR at five years = 0.84, (95% CI; 0.53 to 1.33). At five years the incidence of fluorosis was similar between the groups.ConclusionsThere is no evidence that fluoride supplements taken by women during pregnancy are effective in preventing dental caries in their offspring.