Association of Iodine-Related Knowledge, Attitudes, and Behaviours with Urinary Iodine Excretion in Pregnant Women with Mild Iodine Deficiency

Background: China’s universal salt-iodization program has all but eliminated iodine deficiency disorders. Concern has shifted to mild iodine deficiency. Our study examined factors with the potential to predict mild iodine deficiency in pregnant women. Methods: A total of 2 400 pregnant women were enrolled using a multistage, stratified, random-sampling method. Data were collected through face-to-face interviews, a standardized questionnaire, an iodine-related knowledge questionnaire, urine samples, and household cooking salt samples. Results: The median urinary iodine concentration (MUIC) was 148.0 μg/L for all participants, and 155.0 μg/L, 151.0 μg/L, and 139.6 μg/L in the first, second, and third trimesters, respectively. The third trimester’s MUIC was significantly lower than that of the first trimester, and the usage rates of iodized salt and qualified-iodized salt were 71.5% and 59.4%, respectively. Iodine-related knowledge was significantly different between the high and low UIC groups. Participants’ MUIC increased significantly with increases in iodine-related knowledge. The third trimester was a significant risk factor for high UIC, whereas abundant iodine-related knowledge, study the dietary knowledge urgently, and consumption of iodine-rich food within 48 hours of a urine iodine test were significant protective factors for high UIC (P<0.05). Conclusions: Iodine levels are adequate among pregnant women in Shanghai during the first and second trimesters, but insufficient in the third trimester. The use of iodized cooking salt does not determine the iodine status of pregnant women. Abundant iodine-related knowledge is important for pregnant women in the third trimester to maintain adequate urinary iodine.