To prevent iodine deficiency disorders, the World Health Organization, United Nations Children's Fund, and International Council for the Control of Iodine Deficiency Disorders established that for a given population median urinary iodine concentrations (UIC) must be 100-199 microg/L in clinically healthy subjects and 150-249 microg/L in clinically healthy pregnant women. We evaluated whether in the urban area of Rome, Italy, where a salt iodination program (30 mg/kg) was introduced since 2005, an increased demand of iodine during pregnancy is guaranteed.