Iodine is widely present in nature and it is one of the essential trace elements for human body. Iodine affects normal growth, development and metabolism of human body by participating in the synthesis of thyroid hormones. Iodine deficiency affects nearly 1.9 billion people worldwide and it is one of the health problems of global concern. As a special group, pregnant women are the focus group of iodine deficiency. Iodine deficiency during pregnancy will not only lead to thyroid dysfunction, endemic cretinism, but also irreversibly affect fetal brain development, resulting in infant mental retardation and growth retardation. This article summarizes the research progress of iodine deficiency during pregnancy, focusing on the hazards and evaluation index of iodine deficiency during pregnancy, and provides reference for future research priorities of iodine deficiency during pregnancy.

Objective:To learn about the iodine nutritional status and thyroid function of pregnant women in the areas of oral lipiodol pills in Xinjiang Uygur Autonomous Region (Xinjiang).Methods:In October 2019, using the probability proportionate to size sampling (PPS sampling) method, Aksu Prefecture (Aksu) of Xinjiang was divided into 5 sampling areas according to the directions of east, west, south, north and middle. One county was selected from each area, one township was selected from each county according to the directions of east, west, south, north and middle, and 20 pregnant women were selected from each township. The general demographic data of pregnant women were collected by questionnaires, and 24-hour urine samples, household salt samples and drinking water samples were collected for iodine detection, and serum samples were collected for thyroid function index detection.Results:A total of 555 pregnant women were investigated, including 121, 234 and 200 women in the early, middle and late pregnancy, with an average age of 26 years. Among them, the median of urinary iodine of women in early, middle and late pregnancy was 209.53, 204.27 and 225.29 μg/L, respectively, which was all in the appropriate state. The median of salt iodine was 24.70, 26.00 and 26.20 mg/kg, respectively, and the median of water iodine was 4.85, 3.30 and 4.85 μg/L, respectively. There were no significant difference in urinary iodine, salt iodine and water iodine during different pregnancy ( H= 1.61, 4.38, 2.63, P > 0.05). The prevalence rate of subclinical hypothyroidism, subclinical hyperthyroidism and hyperthyroidism in pregnant women was 4.32% (24/555), 0.54% (3/555) and 0.36% (2/555), respectively; and the highest prevalence rate was in the middle pregnancy, which was 7.26% (17/234), 1.28% (3/234) and 0.85% (2/234), respectively. The positive rate of autospecific antibody in pregnant women with normal thyroid function was 13.15% (73/555). The positive rate of thyroid peroxidase antibody (TPOAb) and thyroglobulin (TgAb) was 11.35% (63/555), 8.11% (45/555), respectively. After excluding the pregnant women with positive thyroid autospecific antibody, the range ( P2.5- P97.5) of thyroid stimulating hormone (TSH) in different pregnancy were close to or slightly higher than the recommended reference value in the "Guideline on Diagnosis and Management of Thyroid Diseases During Pregnancy and Postpartum (2nd ed)". Except that the P2.5 value of free thyroxine (FT 4) in early pregnancy was lower than the reference value, the FT 4 range in other pregnancy showed the same trend as that of TSH. The results of Spearman correlation analysis showed that free triiodothyronine (FT 3) and FT 4, TPOAb and TgAb, TgAb and FT 4 were positively correlated ( r= 0.497, 0.504, 0.216, P < 0.05), and TSH and FT 3 was negatively correlated ( r = - 0.194, P < 0.05) in the early pregnancy; FT 3 and FT 4, TPOAb and TgAb were positively correlated in the middle and late pregnancy ( r = 0.188, 0.527, 0.177, 0.623, P < 0.05); TSH was negatively correlated with FT 3 in the late pregnancy ( r = - 0.165, P < 0.05); there was no correlation between urinary iodine and thyroid function indexes ( P > 0.05). Conclusions:The water iodine in the outer environment of the oral lipiodol pills area Aksu in Xinjiang is low, and the iodine nutrition level of pregnant women is appropriate. Except that the P2.5 value of FT 4 in the early pregnancy is lower than the reference value, the TSH range close to or of women during each pregnancy and the FT 4 range of women in the middle and late pregnancy are slightly higher than the reference value, which still need continuous monitoring.

Objective:Through the detection of iodine nutrition level and thyroid function of pregnant women in Xinjiang Uygur Autonomous Region (Xinjiang), to preliminary study the pregnant women's iodine nutrition level, thyroid function status and the relationship between the two and influencing factors.Methods:From March to June in 2020, stratified cluster random sampling method was adopted. Two counties (cities) in Southern and Northern Xinjiang were selected as survey sites, and about 100 pregnant women (a total of 412) were selected from each county (city) as survey subjects. Random urine samples and blood samples were collected to detect urinary iodine and serum thyroid function indicators [thyroid stimulating hormone (TSH), free triiodothyronine (FT 3), free thyroxine (FT 4), anti-thyroglobulin antibody (Tg-Ab) and anti-thyroid peroxidase antibody (TPO-Ab)]. Results:The median and interquartile range [ M ( Q1, Q3)] of pregnant women's urinary iodine was 228.4 (143.15, 327.95) μg/L. Serum FT 3, FT 4 and TSH levels [ M ( Q1, Q3)] were 4.22 (3.92, 4.61), 13.79 (12.63, 15.26) pmol/L and 1.82 (1.26, 2.52) mU/L, respectively. The overall positive rates of Tg-Ab and TPO-Ab were 5.61% (23/412) and 11.95% (49/412), respectively. The positive rates of Tg-Ab and TPO-Ab in Southern and Northern Xinjiang were 4.78% (10/209), 10.05% (21/209), 6.40% (13/203) and 13.79% (28/203), respectively. The positive rates of Tg-Ab and TPO-Ab in Northern Xinjiang were higher than those in Southern Xinjiang, but the difference was not statistically significant (χ 2 = 1.31, 2.17, P > 0.05). The positive rate of TPO-Ab in pregnant women was the influencing factor of abnormal thyroid function, and the odds ratio ( OR) [95% confidence interval ( CI)] was 3.22 (1.31 - 7.93). Conclusions:Pregnant women in Xinjiang are generally at an appropriate level of iodine, but the state of thyroid function still needs continuous attention. In addition, it is necessary to strengthen the thyroid function examination of pregnant women with positive thyroid autoantibodies to prevent and control the occurrence of abnormal thyroid function in pregnant women.