Introduction Iodine is scarcely found in food products of many regions through the world. Scientific findings have suggested that providing adequate iodine during pregnancy prevents many adverse effects of iodine deficiency (ID) in newborn babies. Therefore, Pregnant women are a special group in this context.

Material & method 1078 pregnant women at their first prenatal care from five districts of Urmia City, north west of Iran, were interviewed. Of these, 490 were qualified and followed until delivery. Urine and sera samples were collected at two stages (1st & 3rd trimester). Data of demographic features and iodised salt accessibility were gathered through a questionnaire.

Results Mean age (SD) of studied people was 25 (5.4) years. All households had proper access to iodised salt. Median of Urinary iodine excretion (UIE) was 73.5 μg/l as a whole at 1st trimester. This raised to 114 μg/l at 3rd trimester. According to WHO criterion, 87% and 70% iodine deficiency (ID) was detected at 1st & 3rd trimester, respectively. Quantile regression models for 1st` trimester showed educational status, way of using iodised salt, and geographical situation as determinant factors in first&third quartile of UIE. The same results were observed at 3rd trimester.

Conclusion Nearly 20 years after salt iodisation program in Iran, there are pockets of iodine deficiency even in a close vicinity. Education and knowledge about using iodised salt are major determinant factors in iodine intake of pregnant women. It seems that more practice on this context is needed to assure adequate access to iodine generally and for pregnant women specifically.