Nutritional Iodine Status in Gestation and its Relation to Geographic Features in Urmia County of Northwest Iran

Abstract

Iodine is an important component for the proper function of the thyroid and fetal development. To evaluate the influence of geographic variation on nutritional iodine status during pregnancy. Four hundred eighty-nine women in the first trimester of pregnancy were enrolled. Of these, 419 (85.5%) were from the plain districts and 70 (14.5%) from mountainous regions. Data were obtained on demographic characteristics and accessibility of iodized salt, and samples of table salt were collected. In the third trimester, 322 women remained in the study: 281 (87.2%) from the plains and 41 (12.8%) from the mountainous regions. Salt and urine samples were analyzed for iodine content. All participants stated that they used iodized table salt. The proportion of salt samples with optimal iodine content (30 ppm) from the plains and mountain regions were 68.7% and 88%, respectively. The median urinary iodine content (UIC) in the plains area in the first and third trimesters was 82 and 119 microg/L, respectively. The corresponding values in the mountain region were 34.5 microg/L and 76 microg/L. The prevalence of subjects with an inadequate iodine intake (UIC < 150 microg/L) in first and third trimester in the plains and mountain regions were 84.5% and 66.9% vs 98.6% and 90.2%, respectively. The prevalence of pregnant women exhibiting UIC < 150 microg/L in the mountain region was substantially higher than those in the plain district. Our findings also show that the current strategy for eradication of iodine deficiency in school-aged children would not fulfill iodine requirements in pregnancy and that additional source(s) of iodine are required to prevent the adverse effects of iodine deficiency in pregnancy. Further studies are needed to address the cause(s) for the rapid depletion of iodine stores in pregnancy.