Objective - to optimize a method for the prevention of iodine deficiency in pregnant women. Subject and methods. One hundred and seventy pregnant women living in the Saratov Region, a moderate iodine-deficiency area, were followed up. A vitamin-mineral complex containing 150 µg iodine (a daily dose) was given to Group 1 pregnant women (n = 40) in the first trimester. Group 2 pregnant women (n = 40) received iodomarin 200 µg/day in the early periods of pregnancy. Group 3 consisted of 90 women who had taken iodomarin 200 µg/day before conception and 250 µg/g of this drug throughout pregnancy and breastfeeding. Results. The trial showed the benefit of the daily continuous administration of 200 µg potassium iodide as a component of iodine monopreparation (iodomarin) from the pregravid stage, by further increasing its dose up to 250 µg/day throughout pregnancy and breastfeeding as compared to that of 150 µk iodine as a component of vitamin-mineral complexes or 200 µg potassium iodide from the first trimester of pregnancy. Conclusion. The optimal method to prevent iodine deficiency states during pregnancy in the patients living in iodine deficiency areas is the continuous intake of potassium iodide (iodomarin) in a dose of 200 µg/day from the pregravid period, by increasing the dose up to 250 µg/day throughout pregnancy and breastfeeding.