To avoid iodine deficiency and its consequences in pregnant women and their offspring, women should reach a sufficient iodine intake long before conception. To monitor iodine status, median urinary iodine concentration (UIC) is widely used in pregnant women (PW). Thyroglobulin (Tg) us another marker used to assess iodine status . In this study, urine samples as well as dried blood spots will be collected to measure UIC and Tg (as well as other hormones to define thyroid function) in PW. The results shall be used to reassess the threshold which defines iodine status in PW according to UIC.