Background & Aims: Maternal anemia in pregnancy is a considerable risk factor for both mother and fetus. Growth retardation, intra uterine fetal death, maternal cardiovascular symptoms and reduction in blood supply are among outcomes of maternal anemia. Since there are different reports about the relationship between low maternal hemoglobin level and low birght weight, the precent study was designed to determine the relationship of maternal iron deficiency in pregnancy and umbilical cord cortisol level with neonatal weight and length. Methods: This cross-sectional study was done on 500 pregnant women reffered for elective cesarean. At first, blood sample was taken for determining hemoglobin level. Then, in anemic ones (Hb<11), blood sample was taken to determin iron deficiency indices. After cesarean, blood sample was taken for determining the umbilical cord cortisol level. Data were analyzed through SPSS 20. Results: In mothers with normal hemoglobin, neonate’s weight and length were significantly higher (P=0.030, P=0.039). Umbilical cortisol level had a significant relationship with birth weight and length (P=0.001, P=0.001), but there was no significant correlation between maternal hemoglobin level and umbilical cord cortisol level. Conclusion: Maternal anemia changes the angiogenesis in placental vessels and causes growth retardation and pregnancy complications due to creating stress in mother and increasing CRH. The results of this study highlight the importance of maintaining the hemoglobin level in normal range with prescription of iron products in iron deficiency anemia and removing the risk factors of maternal hemoglobin increment. Due to the meaningful relation between umbilical cord cortisol with birth weight (direct relation) and length (indirect relation), more studies about the maternal anemia, maternal cortisol and another factors influencing on umbilical cord cortisol level are suggested.