Iodine deficiency in pregnancy is prevalent in vulnerable groups in Denmark.

INTRODUCTION Iodine is essential for the production of thyroid hormones. In pregnancy, physiological changes occur that can lead to iodine deficiency and impairment of fetal neurological development. We aimed to assess the iodine intake in pregnant women in Eastern Denmark, compare iodine levels in Eastern and Western Denmark and to identify potentially vulnerable groups. METHODS This was a cross-sectional cohort study of pregnant Danish women (n = 240). Questionnaires and urine samples were collected at the Ultrasound Clinic, Hvidovre Hospital, Denmark, and urinary iodine concentrations (UIC) (µg/l) were measured. Predictors of iodine supplement use were examined by multivariate logistic regression models. RESULTS The pregnant women from Eastern Denmark had a median age of 30 years and the median gestational week at which they were included in the study was week 19. The majority took iodine-containing supplements (86%). The median UIC was 118 (interquartile range (IQR): 79-196) µg/l in iodine supplement users and 82 (IQR: 41-122) µg/l in non-users (p < 0.001). Predictors of not using iodine supplement in Eastern and Western Denmark were short maternal education, non-Danish origin and pre-pregnancy obesity. CONCLUSIONS The iodine status in Danish pregnant women was below WHO recommendations. Iodine supplement non-users are at a particular risk of iodine deficiency. Low maternal education, non-Danish origin and pre-pregnancy obesity are predictors of non-iodine supplement use. An increase in iodine fortification may be recommended to improve the iodine status in pregnant Danish women. FUNDING none. TRIAL REGISTRATION not relevant.