BACKGROUNDAccording to WHO statistics of 2013, daily 371,124[1] births, annually 135.5 million [1] births occur worldwide which tends to increase in the following years. In Mongolia, studies that evaluaterelationship between fluid intakes of pregnant women and preterm delivery risk have not been conducted so far to our knowledge. Thus, we aimed to determine this relationship by evaluating first and second trimester fluid intakesof pregnant women in Mongolia.METHODS35 and above years old pregnant women of 24-32 gestational weeks have been included in the study where body measurements and fluid intake were collected via questionnaireand examination.RESULTSWhen we studied the relationship between average fluid intake and preterm delivery risk, having inadequate fluid intake in the first trimester increased the risk of preterm delivery by 5.98 (CI95% 0.89-40.08, p<0.01) fold whereas having inadequate fluid intake in the second trimester increased the risk of preterm delivery by 4.03 (CI 95% 1.06-15.21, p<0.01) foldrespectively.CONCLUSIONSOur results show that low fluid intake in first and second gestational trimesters results in increased risk of preterm delivery significantly in Mongolia.