Insufficient iodine status in pregnant women as a consequence of dietary changes

Background: Historically, Iceland has been an iodine-sufficient nation due to notably high fish and milk consumption. Recent data suggest that the intake of these important dietary sources of iodine has decreased considerably. Objective: To evaluate the iodine status of pregnant women in Iceland and to determine dietary factors associated with risk for deficiency. Methods: Subjects were women (n = 983; 73% of the eligible sample) attending their first ultrasound appointment in gestational weeks 11–14 in the period October 2017–March 2018. Spot urine samples were collected for assessment of urinary iodine concentration (UIC) and creatinine. The ratio of iodine to creatinine (I/Cr) was calculated. Median UIC was compared with the optimal range of 150–249 µg/L defined by the World Health Organization (WHO). Diet was assessed using a semiquantitative food frequency questionnaire (FFQ), which provided information on main dietary sources of iodine in the population studied (dairy and fish). Results: The median UIC (95% confidence interval (CI)) and I/Cr of the study population was 89 µg/L (42, 141) and 100 (94, 108) µg/g, respectively. UIC increased with higher frequency of dairy intake, ranging from median UIC of 55 (35, 79) µg/L for women consuming dairy products 2 times per day (P for trend