Prevalence of vitamin D and calcium deficiencies and their health impacts on women of childbearing age: a protocol for systematic review and meta-analysis

Introduction No systematic reviews has synthesised data on the available evidence to determine the prevalence of calcium and vitamin D deficiencies as a public health problem globally. Therefore, this study presents a protocol for conducting a review and meta-analysis to estimate the prevalence of calcium and vitamin D serum deficiencies in women of childbearing age and stratify these data by age group, urban and rural area, world region and pregnant/non-pregnant women whenever possible. Methods and analysis The systematic review protocol involves conducting a literature search in the following databases: PubMed, LILACS, Embase, Scopus and Web of Science. The selected articles will be checked thoroughly, including the references to include grey literature. Cross-sectional studies and baseline data from cohort studies or clinical and community trials conducted with women of childbearing age with representative probabilistic sampling will be included. Two independent researchers will be responsible for article selection and data extraction, and discrepancies, if any, will be dealt with by a third reviewer. Methodological quality and risk of bias will be analysed using the Grading of Recommendations, Assessment, Development and Evaluations and Joanna Briggs Institute's checklist, respectively. The heterogeneity of the estimates between studies will also be evaluated. Dissemination of the key findings from the systematic review will help identify priorities for action, establish dietary guidelines, develop health-related public policies and reduce and combat micronutrient deficiencies among women of childbearing age and their children. Ethics and dissemination Formal ethical approval is not required, and findings will be published in a peer-reviewed journal. PROSPERO registration number CRD42020207850.