Iodine Deficiency and Excess in Brazilian Pregnant Women: A Multicenter Cross-Sectional Study (EMDI-Brazil)

Background/Objectives: Iodine is an important nutrient for the human body, used in the production of thyroid hormones. During pregnancy, a deficiency can cause miscarriage and hypothyroidism, while an excess can cause thyroid dysfunction. Therefore, the objective of this study was to evaluate the factors associated with the iodine nutritional status of pregnant Brazilian women. Methods: This was a cross-sectional, multicenter study conducted with pregnant women over 18 years of age, users of the Unified Health System (SUS). A semi-structured questionnaire was used to obtain sociodemographic information. Iodine status was assessed by urinary iodine concentration (UIC). The iodine content of salt and homemade and industrial seasonings was determined by the titrimetric method. Dietary intake was estimated through a 24-hour dietary recall. The chi-square test and hierarchical multinomial logistic regression were used for statistical analysis. The significance level was set at p ≤ 0.05. Results: Among Brazilian pregnant women, the median UIC was 186.7 µg/L (P25: 118.05 µg/L-P75: 280.93 µg/L). Regarding iodine nutritional status, the prevalence of deficiency was 36.7% (n = 694), above the requirement was 28.7% (n = 543), and excess iodine intake was 3.6% (n = 68). We observed that non-white pregnant women were more likely (OR = 1.83; 95% CI: 1.27-2.64) to have iodine deficiency, and those who did not work were less likely (OR = 0.71; 95% CI: 0.52-0.98). Pregnant women in the last trimester of pregnancy were less likely to have iodine intake above the requirements (OR = 0.52; 95% CI: 0.31-0.88). Conclusions: A substantial proportion of pregnant women had iodine deficiency or intake above the required level. Iodine deficiency is more chance among non-white pregnant women and less chance among those not employed during pregnancy. On the other hand, pregnant women who were in their third trimester of pregnancy were less likely to have iodine intake above the required level.