A contrast analysis of iodine nutrition levels of pregnant women before and after implementing the new standard of iodized salt in Shanxi Province

Objective To study the nutritional status of pregnant women in Shanxi Province before and after the implementation of the new standards of iodized salt content, provide the basis for scientific supplementation of iodine for pregnant women. Methods According to the method of population proportion sampling, 30 county-level monitoring sites were selected, a primary school was selected from each county (city, district) by the method of simple random sampling and 40 students in 2011 or 50 students in 2014 aged 8-10 years were selected in each school, direct titration was used to detect salt iodine; at the same time, 20 pregnant women were selected from each town where the primary school was located and urinary iodine was determined using arsenic cerium catalytic spectrophotometry (WS/T 107-2006). Results A total of 1 182 and 1 437 salt samples was detected in Shanxi Province in 2011 and 2014, the median of salt iodine was 30.5 and 24.1 mg/kg, respectively, and the difference was statistically significant (H= 567.45, P < 0.01); it was 95.41%, 80.31%, 76.62% of the coverage rate of iodized salt, qualified rate of iodized salt, qualified iodized salt consumption rate in 2014, respectively; which were compared with those in 2011 (97.63%, 97.49%, 95.18%), the differences were statistically significant (χ2= 9.27, 232.40, 166.25, P < 0.01). A total of 440 and 630 urinary samples of pregnant women were tested in 2011 and 2014, the median of urinary iodine was 279.6 and 177.1 μg/L, respectively, iodine nutrition of pregnant women was more than adequate in 2011, and iodine nutrition was suitable in 2014. The difference was statistically significant (H= 153.89, P < 0.01). The proportion of pregnant women's median of urinary iodine less than 150 μg/L in 2014 [41.11% (259/630)] was significantly higher than that in 2011 [8.18% (36/440) , χ2= 140.68, P < 0.01]. The constituent ratio of 250 to 500 μg/L was significantly decreased [23.65% (149/630) vs 54.77% (241/440), χ2= 108.33, P < 0.01). Conclusion It is at a reasonable level of iodine nutrition level of pregnant women in Shanxi after the adjustment of iodized salt content, but the ratio of < 150 μg/L is increasing, which needs to be paid attention to. Key words: Salts; Iodine; Pregnant women; Nutrition