Nutritional iodine status in gestation and its relation to geographic features in Urmia County of northwest Iran

Iodine is an important component for the
proper function of the thyroid and fetal development.
Objective. To evaluate the influence of geographic
variation on nutritional iodine status during pregnancy.
Methods. 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.
Results. 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 μg/L, respectively.
The corresponding values in the mountain region
were 34.5 μg/L and 76 μg/L. The prevalence of subjects
with an inadequate iodine intake (UIC < 150 μg/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.
Conclusions. The prevalence of pregnant women
exhibiting UIC < 150 μg/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