Background:The aim of this study was to investigate the relationship between idiopathic microscopic hematuria (in the first and second trimesters) and major adverse outcomes of pregnancy.Materials and Methods:Urinalysis was done for 700 pregnant women before 24 weeks of pregnancy. Those who had 3–5 red blood cells per milliliter in urinalysis were considered positive urinalysis. Then, all individuals were examined for blood pressure and other alarm signs of pregnancy complications in each visit. All mothers were followed for the incidence of preeclampsia, preterm delivery, and pregnancy outcome until the end of pregnancy.Results:The results of this study showed that no significant difference in terms of incident of pregnancy complications between the pregnant women with and without hematuria and the only abortions and neonatal deaths differed between the two groups.Conclusion:These results suggest that further studies are needed to determine whether idiopathic microscopic hematuria can be a predictive value for pregnancy complications or not.