Resumo Objetivo Estimar a prevalência de níveis inadequados de vitamina D e seus fatores associados para mulheres em idade fértil no Brasil. Métodos Uma revisão sistemática foi realizada (última atualização em maio de 2020). As meta-análises foram realizadas usando o inverso da variância para o modelo fixo com cálculo de proporção sumarizada por transformação arco-seno duplo de Freeman-Tukey. A qualidade metodológica e de reporte foi avaliada usando a ferramenta do Joanna Briggs Institute para estudos de prevalência. Resultados Nossa revisão identificou 31 estudos, compreendendo 4.006 participantes. Todos os estudos apresentaram pelo menos uma limitação, principalmente devido ao uso de amostra de conveniência e tamanho amostral pequeno. As prevalências gerais de deficiência, insuficiência e deficiência de vitamina D foram 35% (intervalo de confiança, IC 95%: 34-37%), 42% (IC 95%: 41-44%) e 72% (IC 95%: 71-74%), respectivamente. Conclusão Embora a magnitude da prevalência de níveis inadequados de vitamina D seja incerta, a evidência sugere que presença de deficiência ou insuficiência de vitamina D em mulheres em idade reprodutiva pode causar problemas moderados a graves.

Abstract Objective To estimate the prevalence of inadequate vitamin D level and its associated factors for women of childbearing age in Brazil. Methods A systematic reviewwas conducted (last updatedMay 2020).Meta-analyses were performed using the inverse-variance for fixed models with summary proportion calculation by Freeman-Tukey double arcsine. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool for prevalence studies. Results Our review identified 31 studies, comprising 4,006 participants. All the studies had at least one weakness, mainly due to the use of convenience sampling and small sample size. The overall prevalence of vitamin D deficiency, insufficiency, and both deficiency and insufficiency were 35% (confidence interval, 95%CI: 34-37%), 42% (95%CI: 41-44%), and 72% (95%CI: 71-74%), respectively. Conclusion Although the magnitude of the prevalence of inadequate levels of vitamin D is uncertain, the evidence suggests that presence of vitamin D deficiency or insufficiency in women of reproductive age can cause moderate to severe problems.

ABSTRACT BACKGROUND: Despite the several options available for supplements containing vitamins C and E, evidence regarding the prevalence of deficiency or insufficiency of these vitamins is weak. OBJECTIVES: To estimate the prevalence of deficiency or insufficiency of vitamins C and E and associated factors among women of childbearing age, in Brazil. DESIGN AND SETTING: Systematic review and meta-analysis conducted at a Brazilian public university. METHODS: A search from index inception until May 2020 was conducted. Meta-analyses were performed using inverse variance for fixed models, with summary proportions calculation using Freeman-Tukey double arcsine (base case). Reporting and methodological quality were assessed using the Joanna Briggs Institute tool for prevalence studies. RESULTS: Our review identified 12 studies, comprising 1,316 participants, especially breastfeeding women. There was at least one quality weakness in all studies, mainly regarding sampling method (i.e. convenience sampling) and small sample size. The prevalence of vitamin C deficiency ranged from 0% to 40%. Only vitamin E deficiency was synthetized in meta-analyses, with mean prevalences of 6% regardless of the alpha-tocopherol cutoff in plasma, and 5% and 16% for cutoffs of < 1.6-12.0 mmol/l and < 16.2 mmol/l, respectively. The cumulative meta-analysis suggested that a trend to lower prevalence of vitamin E deficiency occurred in recent studies. CONCLUSIONS: Although the studies identified in this systematic review had poor methodological and reporting quality, mild-moderate vitamin C and E deficiencies were identified, especially in breastfeeding women. Thus, designing and implementing policies does not seem to be a priority, because the need has not been properly dimensioned among women of childbearing age in Brazil. REGISTRATION NUMBER IN PROSPERO: CRD42020221605.

Resumen Antecedentes: A pesar de las políticas actuales de yodación de la sal, la deficiencia de yodo sigue siendo un problema de salud pública mundial, especialmente en las mujeres. Hasta ahora, se han sugerido pruebas contradictorias sobre la prevalencia de la deficiencia de yodo en Brasil. Objetivo: Estimar la prevalencia de deficiencia de yodo y factores asociados en mujeres en edad fértil, en Brasil. Métodos: Se realizó una revisión sistemática, buscando en PubMed, LILACS, OMS, Scopus y la base de datos de disertaciones y tesis de Capes desde el inicio hasta mayo de 2020. Se realizaron metanálisis de proporciones utilizando la variancia inversa para el modelo fijo. La calidad de información y metodológica se evaluó utilizando la herramienta del Institute Joanna Briggs para estudios de prevalencia. Resultados: Nuestra revisión identificó siete estudios publicados entre 2002 y 2017, incluyendo 1354 participantes, especialmente mujeres embarazadas. Todos los estudios presentaron al menos una limitación de calidad, principalmente con respecto al método de muestreo (es decir, la conveniencia) y el pequeño tamaño de la muestra. La prevalencia de la deficiencia de yodo varió entre los estudios del 16% y el 62%, mientras que el metanálisis identificó una prevalencia media del 40% (intervalo de confianza del 95%, IC 37%-43%) para las mujeres embarazadas y del 13% (IC del 95% 4%-24%) para mujeres no embarazadas. El metanálisis acumulativo sugiere una tendencia a una mayor prevalencia de deficiencia de yodo a partir de 2018 en mujeres embarazadas. Conclusiones: Si bien esta revisión sistemática identificó estudios con mala calidad metodológica y de reporte, se identificó una alta prevalencia de deficiencia de yodo en mujeres embarazadas, lo que refuerza la importancia de las políticas nutricionales nacionales para monitorear el estado de yodo en esta población. Los estudios futuros deben considerar el muestreo probabilístico aleatorio, el tamaño de muestra apropiado y el análisis de subgrupos predefinidos para informar adecuadamente la prevalencia de la deficiencia de yodo y los factores asociados en mujeres en edad fértil y para respaldar las políticas de salud.

Abstract Background: Despite current policies of salt iodination, iodine deficiency is still a global public health problem, especially in women. So far, conflicting evidence has been suggested for the prevalence of iodine deficiency in Brazil. Objective: To estimate the prevalence of iodine deficiency and associated factors in women of childbearing age in Brazil. Methods: A systematic review was conducted using databases (PubMed, LILACS, WHO, Scopus, and Capes’ dissertation and thesis), from inception to May 2020. Meta-analyses of proportions were performed using the variance inverse for the fixed model. Reporting and methodological quality were assessed using the Joanna Briggs Institute tool to prevalence studies. Results: Our review identified seven studies published between 2002 e 2017, including 1354 participants, especially pregnant women. All studies presented at least one quality limitation, mainly regarding the sampling method (i.e., convenience) and small sample size. The prevalence of iodine deficiency ranged among studies from 16% to 62%. In contrast, the meta-analysis identified a mean prevalence of 40% (95% confidence interval, CI 37%-43%) for pregnant women and 13% (95% CI 4%-24%) for non-pregnant women. Cumulative meta-analysis suggests a tendency of higher iodine deficiency prevalence from 2018 in pregnant women. Conclusions: Although this systematic review identified studies with poor methodological and reporting quality, a high prevalence of iodine deficiency was identified in pregnant women, reinforcing the importance of national nutritional policies for monitoring iodine status in this population. Future studies should consider random probabilistic sampling, appropriate sample size, and pre-defined subgroup analysis to adequately inform the prevalence of iodine deficiency and associated factors in women of childbearing age and support health policies.