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48 Chapter 1 always been scarce. This used to be the same for Central and South America, however over the past years this has changed due to initiatives of the Functional International Digestive Epidemiological Research Survey (FINDERS) group, which was founded to investigate the epidemiology of functional gastrointestinal disorders in Latin American children. In order to gain more insights into functional gastrointestinal disorders worldwide, it is crucial to study the epidemiology and risk factors in regions where research data are scarce. These insights may eventually provide us with knowledge to develop preventive strategies or more tailored treatment approaches for children with FDDs. No significant association was found between age and prevalence of FDDs. Previous literature has described a higher prevalence rate of FC in toddlers as compared to infants, which is consistent with the reported peak incidence around the age of 2.3 years. 33,54,55 Per the Rome criteria, a clear distinction has been made between children under 4 years of age and older than 4 years of age. Unfortunately, the number of studies on younger children that could be included in the meta-analysis was limited and due to the large variety in reported age ranges, we were unable to perform meta-analysis on other age groups. Several studies have investigated factors that might be associated with FDDs, ranging from dietary factors to psychosocial characteristics. It remains difficult to draw strong conclusions from these predominantly cross-sectional studies. Moreover, study results regarding factors associated with FDDs are at odds with each other. Out of all factors studied, negative psychosocial factors (e.g., stressful life events, internalizing and externalizing problems, low quality of life) seem to be most consistently associated with a higher prevalence of FDDs. On the one hand, it could be hypothesized that negative psychosocial factors are the result of dealing with the bothersome symptoms related to FDDs. On the other hand, the importance of brain-gut interactions in the pathophysiology of functional gastrointestinal disorders is increasingly recognized and psychosocial factors may directly have an effect on the prevalence of FDDs. 56,57 However, a causal relationship cannot be assumed based on the currently available evidence. Longitudinal studies on this topic would be helpful in gaining more insight into the role of these factors in the pathophysiology of FDDs. Some limitations need to be taken into account when interpreting our results. Although we did not limit our search to specific languages to minimize the risk of language bias, we did not search other language databases and therefore may not have identified some non-English publications. Out of the included studies, not all studies specifically stated that they excluded children with organic causes, which could have an effect on our results. However, it is possible that children with organic pathology were excluded from the majority of these studies, even without a specific statement, since the Rome criteria specifically define FDDs as symptoms occurring in the absence of an organic cause and