Maternal iodine deficiency and pregnancy complications

What is it about?

The appropriate maternal thyroxine (T4) and 3,5,3-triiodothyronine (T3) levels during the whole pregnancy are important for the normal fetal development. The levels of maternal thyroid hormones (THs) depend on the concentration of iodine. The level of iodine sharply increases by 50% during the gestation (Zimmermann, 2016) to increase the production of THs and to cover the fetus needs and the elevation in the iodine excretion. During this stage, fetuses get a fraction of maternal THs and iodine ingredient in the placenta and amniotic fluid. On the other hand, thyroid disorders, iodine deficiency, and thyroid autoimmunity during the gestation could alter the maternal hemostasis and the fetal development. In women, severe maternal iodine deficiency is associated with spontaneous abortion, stillbirth, endemic cretinism, fetal growth restriction (FGR), preterm delivery, low birth weight (LBW), and neurological damage The marginal iodine deficiency can disrupt the interactions between Bergmann glia cells (BGs) and Purkinje cells (PCs), and between the regulation of the glutamate transporter and receptor. The gestational inadequate iodine intake can delay the maturation of the developing brain from mild intellectual reduction to frank cretinism, which is the main avoidable reason for mental defects. Thus, the present view suggests that the balance in the activities of THs and in the concentration of iodine during the gestation can keep the regular associations between the dams and their fetuses. In addition, any disorders or deficiency in the concentration of iodine during the gestation may cause multiple pregnancy complications, maternofetal hypothyroidism, and delay the fetal development, in particular, the developing brain. Thus, adjustment the urine iodine concentrations of pregnant women should be followed to avoid any disorders in the maternal iodine and in the fetal development. As well, iodine nutrition or supplementation may be required during the gestation. However, additional studies are warranted to investigate the effects of all types of thyroid dysfunctions and gestational iodine nutritional surveillance on the fetal/neonatal outcomes.

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Why is it important?

The present view suggests that the balance in the activities of THs and in the concentration of iodine during the gestation can keep the regular associations between the dams and their fetuses. In addition, any disorders or deficiency in the concentration of iodine during the gestation may cause multiple pregnancy complications, maternofetal hypothyroidism, and delay the fetal development, in particular, the developing brain. Thus, adjustment the urine iodine concentrations of pregnant women should be followed to avoid any disorders in the maternal iodine and in the fetal development. As well, iodine nutrition or supplementation may be required during the gestation.

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