Objective To understand the iodine nutrition levels of pregnant women in Xigu District of Lanzhou City from 2017 to 2018, and provide a reference for improving the iodine nutrition status as well as a theoretical basis for the iodine supplementation strategy for pregnant women in this area.

Method Stratified sampling method was performed to randomly select 200 pregnant women from Xigu District of Lanzhou City, of which the household edible salt samples and single urine samples were collected. The iodine nutrition levels, residents' coverage rates and pass rates of iodized salt in Xigu District were analyzed. Urinary iodine was determined with the National Standards of "Arsenic-Cerium Catalytic Spectrophotometry of Iodine in Urine, " and salt iodine was determined by direct titration.

Results Analysis of iodine nutrition levels among pregnant women in Xigu District of Lanzhou City between 2017 and 2018 revealed the following. ① The median urinary iodine of pregnant women was under 150 μg/L, indicating that iodine nutrition was insufficient. Nonparametric Wilcoxon rank sum test showed that there was no significant difference in the median urinary iodine between two years (Z=-0.60, P=0.548) as well as different trimesters (Z_1st=-1.10, P=0.273; Z_2nd=-0.12, P=0.908; Z_3rd=-0.06, P=0.949). ②The median iodine content of edible salts at pregnant women household was 23.50 mg/kg for both years with the pass rates 74.0% and 83.0%, respectively. Neither of which reached the the standards of iodized salt rate over 90%. According to the Chi-square test, the difference of the pass rates of iodized salt for pregnant women in Xigu District of Lanzhou City was statistically significant between 2017 and 2018 (χ²=94.95, P=0.01). The coverage rate of iodized salt reached 98. 0% in both years.

Conclusions Iodine nutrition levels of pregnant women in Xigu District of Lanzhou City between 2017 and 2018 were relatively low, especially the pass rate of iodized salt was lower than the national standard. Therefore, the supervision of salt-producing companies should be strengthened to improve the pass rates of iodized salt. In addition, the significance and method of scientific iodine supplementation should be promoted among pregnant women and their families through health education, in order to prevent the occurrence of iodine deficiency disorders, thereby improving the health status of the whole population.