Introduction: Urinary iodine concentration is used as an indicator of iodine deficiency in pregnant women. However, there is not enough evidence if these laboratorial results have relationship with important maternal, neonatal and infant outcomes.
Objectives: This study aims to evaluate if low levels of urinary iodine concentrations in pregnant women, when compared with normal levels, are associated to prejudice on maternal, neonatal and infant outcomes.
Methods: A systematic literature review will be carried out according to the methodology of the Joanna Brigs Institute (JBI) to risk and etiology studies. We will include prospective cohort studies in which pregnant women with low urinary iodine concentration were compared to pregnant women with normal urinary iodine concentration. The maternal primary outcomes analyzed will be hypothyroidism and preterm birth; the neonatal/infant will be perinatal mortality, low birthweight, neonatal hypothyroidism or elevated thyroid stimulating hormone (TSH). Four general and adaptive search strategies have been created for the following electronic health databases: Embase, Medline and LILACS. The selection process, data extraction and evaluation of the risk of bias will be carried out independently by two reviewers. The risk of bias will be assessed according to the JBI instrument for evaluating risk of bias in etiology and risk studies. Similar outcomes measured in at least two trials will be plotted in the meta-analysis using the software JBI SUMARI. The analysis model in the meta-analysis will be random effects. The quality of the evidence will be generated according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation).
Parcial Results: At first, 5847 articles were selected for initial selection. These articles were transferred to the Rayyan platform, where two reviewers independently are selecting the articles identified by the literature search. On this platform, the title and summary of all articles are being read, dividing them into 3 categories: excluded, included and maybe, according to the fulfillment of the eligibility criteria determined in the review protocol. The potentially eligible studies for inclusion in this review will be selected for full reading and evaluated for suitability to the proposed PECO structure. In case of disagreements, there will be a debate between the reviewers and a third party before the final decision. The study selection flowchart will be created according to the PRISMA guidelines.
Conclusions: The results generated by this review may help to decide to supplement or not iodine for pregnant women with deficit of this element.