Exposure and Predictive Factors of Postural Development from the Perspective of the Reliability of Their Measurement Tools: A Systematic Review

Postural alignment can be influenced by intrinsic and extrinsic factors; failure to control these confounding factors and the use of invalid tools increase the risk of bias and may distort the results. <b>Objective:</b> The first objective is to identify the confounding factors that may influence the evaluation of body posture in children. The second objective is to determine which methods or tools are used to analyze postural alignment and to review the evidence regarding their validity and reliability, in order to strengthen the credibility of the results obtained. <b>Methods</b>: A systematic review was performed following the PRISMA 2020 criteria. Eligible studies were searched in the Virtual Health Library, Scopus, Medline, Web of Science, PEDro, and the Cochrane Library throughout the entire month of December 2024. Observational studies written in English, Portuguese, or Spanish that analyzed body posture (as the dependent variable) in children under 12 years of age were included. Articles not available in full text or those that assessed only a single body region were excluded. The methodological quality of the studies was assessed using the Newcastle-Ottawa scale, while the ROBINS-E tool was used to assess risk of bias. The synthesis of results was presented as a narrative review. <b>Results:</b> A total of 42 observational articles were included. No meta-analysis was conducted, and the findings are synthesized through a narrative review. The ROBINS-E tool showed a generalized result of high risk of bias, while the Newcastle-Ottawa scale reported moderate quality for longitudinal and case-control studies, with worse scores for cross-sectional studies. Methodological limitations: The differences found in the designs, population, and outcome measures generate high methodological variability that limits the possibility of quantitative synthesis. Likewise, the available evidence on the reliability of the tools is insufficient, which conditions the interpretation of the reported results. <b>Conclusions:</b> The findings with the strongest scientific support suggest that anthropometric variables or those related to body composition may be associated with body alignment. By contrast, there is still controversy regarding the influence of sex and age on postural variables. Sport modality or the weight of the school backpack could also play a role in posture; however, more high-quality studies are needed to contrast the results. The quality of the evidence is limited by heterogeneity in study designs, insufficient control of confounding factors, and the use of tools with inadequate validity and reliability. <b>Other:</b> The study was registered in PROSPERO under the number CRD42024618753. This research received no external funding.