Should this study be trusted to support decision making? Please rate your confidence (1=lowest confidence; 10=highest confidence) in the study design and methods used. Please explain your rating

Answer Explanations

• 10

  user-848112
  Anything form of chemical that compromises the intelligence of a community especially children, who fall into the vulnerable group, should be thoroughly investigated. 
• 8

  user-984299
  More studies are required including more cohorts to discard confounding factors.
• 3

  user-481327
  Covariates used in analysis are different for each outcome, disparate according to gender, and correlate less with Mean Urine Fluoride (which would bioplausibly should be MOST associated with results if true) compared to (self-reported) Fluoride 'intake'. No covariate adjustment for parental income, or any educational programs that each child received up to that point. Very specific setting (Canada cities), and moderate-low amount of sample size (~500 here, compared to over 200 STUDIES present that collectively deal with hundreds of thousands of persons). Current meta-analysis of many studies on fluoridation: https://www.bmj.com/content/321/7265/855.short .
• 9

  user-569374
  The study uses two methods to assess gestational fluoride exposure 1) maternal urinary fluoride concentration and 2) estimated total fluoride intake from maternal consumption questionnaire data and water fluoride concentrations. The second method lends itself to a high change of exposure misclassification due to the self-reported nature of the consumption data, use of water fluoride concentrations exclusively from the primary residential location (and not work/other locations), does not include potential fluoride intake from other sources, among other potential issues. It is unclear why the authors did not control both models for prenatal secondhand smoke exposure, as there is no reason to suggest that it would be a potential confounding factor for the association between estimated fluoride intake and IQ but not for measure urinary fluoride levels and IQ - this makes model comparison more difficult. Additionally, several notable covariates were not assessed as potential confounders including parental IQ scores, household income, maternal employment during pregnancy, etc.
• 5

  user-868575
  It can support decision making to some degree but not alone. Too many confounding factors/covariates, tap water levels were not measured.
• 6

  user-480186
  Although I am not sure about this particular study, there are several other studies indicating  negative neurobehavioral effects of fluorine exposure through drinking water. More importantly, water fluoridation is not necessary as topical fluoride administration appears to safer, more effective to prevent dental caries and is widely available.
• 1

  user-965103
  Most importantly, the authors don't seem to realize that children born in areas with fluoridated water will continue to have increased fluoride exposure after birth. The conclusions of the study focus on exposure during pregnancy, but the observed associations may very well have resulted from exposure during the subsequent 3 to 4 years.
  From a water-fluoridation-policy perspective this may be less important, as lowering the fluoride content of the water would be the solution in either case. In terms of advice for pregnant women, or people raising small children, there could be important differences though.
  
  Further, without a clear biological explanation for the observed difference between boys and girls, and in the presence of multiple earlier studies showing no such difference, I find it doubtful that this difference is more than a chance association.
  If that's what it is, then you could also wonder whether it is chance that you do see an association in boys, or that you don't see one in girls. Either would be equally likely, casting doubt over the reliability of any conclusions from this study.
  
  In conclusion: although some tentative conclusions might be possible, these should be used solely to guide further research, as this study doesn't seem robust enough to base any kind of policy decisions on.
• 6

  user-416789
  Small effect size, moderator not expected a priori -- also, why moderation and not covariate?
• 7

  user-134615
   The study design—a prospective cohort study—is appropriate for assessing the relationship between maternal fluoride exposure and offspring IQ. The researchers utilized urinary fluoride concentration as a biomarker of exposure, which provides a direct and quantifiable measure. However, there are concerns about potential confounders, variability in fluoride metabolism, and the representativeness of the sample population. While these issues do not invalidate the study, they limit the generalizability and strength of the conclusions. Thus, while the study is credible and contributes valuable insights, its findings should be interpreted cautiously when informing policy decisions. 
• 6

  user-603573
  The study has good sample size and it has minimised the errors of measuring urinary fluoride level by analysing 3 serial samples. 
• 2

  user-319692
  It is a small study of children at one specific age that lost participants at multiple steps. It uses IQ scores from only one type of test, and does not adequately account for numerous potential confounders. There are a lot of assumptions about the level of maternal consumption, and it is unclear whether effects measured in children are related to maternal consumption or child's own consumption 
• 1

  user-777357
  Low IQ scores in children are only seen in populations with intakes above recommended levels.
• 7

  user-698496
  A larger study with more diverse population and more frequent urine analysis would be required
• 7

  user-881218
  Fluoride intake data included self reports of mothers and Fluoride intake of around 27% of children was unknown.
• 5

  user-349303
  If it is one out of 10 studies, yes. If it is THE study - no. Comparisons with similar demographics in another country would be required
• 4

  user-466972
  There are some factors didn't considered 
• 2

  user-881150
  this study in itself is indeterminate. It needs supporting evidence over time
• 5

  user-163602
  More refined  and expanded methods are required 
• 6

  user-368556
  Similar studies should be conducted to support the conclusion.
• 6

  user-520332
  Confounded such as micronutrients deficiencies,  environmental factors and other post natal factor should be included. 
  The proportion of sample size between fluorinated and non fluorinated should be proportional. 
  
  
• 5

  user-751579
  I believe the model specification in the employed statistical analysis is inadequate to account for data structure and potential sources of heterogeneity.