Implications of iodine deficiency by gestational trimester: a systematic review

Abstract

As pregnant women are susceptible to changes in iodine, which can cause miscarriage, goiter, thyroid nodules, hypothyroidism, in addition to fetal neurological impairment or development. The aim of this study was to verify the implications of the iodine alteration in each gestational trimester and its consequences of physiological justification. The review was based on PRISMA. Searching for articles that took place in March 2020 without delimiting data. As bases consulted were the Clinical Trials, Cochrane Library, Lilacs and Medline (PubMed). The descriptors were combined as follows: "pregnancy" AND "iodine deficiency". Articles that addressed iodine deficiency and its implications were included. The selection followed the steps of reading the titles, abstracts and full articles. To assess the methodological quality of the studies, the STROBE Instruction instrument was used. The research resulted in 1,266 studies and 11 were included. In assessing methodological quality, the lowest score was and the maximum 20. According to studies, the fourth most affected by iodine loss are the second and third, it is possible to increase the volume and pneumatic nodules, subclinical hypothyroidism, pre-eclampsia, among others. The damages caused by iodine deficiency in the first or second trimester are still reversible, therefore, they need to be diagnosed early, to guarantee an iodic homeostasis and prevent damage to the health of the mother-child binomial.

Nutritional status of iodine in pregnant and non-pregnant adolescents assisted at the Family Health Strategy in Vespasiano, MG

“…23,24 Low iodine intake during pregnancy is associated with restricted fetal growth, higher prevalence of preeclampsia, increased risk of sub-fertility, and preterm delivery. 24,25 Furthermore, depending on the gestational period, impairment due to deficiency differs, 26 and at early ages of pregnancy there is a greater association with delay in neuropsychomotor development, since the brain is particularly sensitive to this deficiency, leading to changes in behavior and decreased cognitive abilities in the offspring, problems in attention and visual processing, as well as changes in motor skills; 14,23 as from 20 weeks is related to fetal distress, musculoskeletal malformations and small fetuses for gestational age. 14,23 Iodine deficiency can last until the sixth week after delivery, when urinary iodine levels gradually increase.…”

Understanding the Pathogenesis of Gestational Hypothyroidism

“…A recent systematic review by Candido et al. ( 34 ) clearly classify the adverse effects of light, moderate and severe iodine deficiency amongst pregnant women between the three trimesters. In pregnant women with moderate iodine deficiency, subclinical hypothyroidism, pre-eclampsia, anemia, fetal growth restrictions, congenital anomalies were observed while in pregnant women with severe iodine deficiency, eclampsia, placenta previa, cretinism, miscarriage, hemorrhage and fetal demise were observed.…”

Low serum triiodothyronine and potassium levels are associated with increased risk of eclampsia among women in the Eastern Cape Province of South Africa

“…Although preeclampsia complicates 5-10% of all pregnancies worldwide, eclampsia, one of the most severe complications of preeclampsia, is associated with 8fold maternal mortality compared to preeclampsia [1,2]. Thyroid dysfunction, iodine and potassium deficiency in pregnancy have all been associated with preeclampsia [3][4][5][6]. However, there is paucity of data on the thyroid function status, iodine nutrition status, as well as the serum potassium levels of women with eclampsia.…”