Pregnancy considerably increases iron needs in a mother and her fetus. The purpose of this study was to assess the relationship between maternal hemoglobin concentration in labor with neonatal birth weight.A population-based study in Shahid Sadughi Hospital in Yazd, Iran, was performed by comparing 1842 singleton term pregnancies of patients with and without anemia and their newborns. Maternal characteristics, including hemoglobin values, were recorded at the labor visit. Maternal anemia was defined as hemoglobin concentration lower than 10 g/dl during pregnancy. Main outcome measures included birth weight and Apgar score. Linear and logistic regression models were used to analyze data.Anemia (Hb 13 g/dl) increased the risk of low birth weight but it was not significant. The risk of a low Apgar score was significantly increased in women with anemia. The minimum incidence of low birth weight occurs in association with a hemoglobin concentration of 10-13 g/dl.Maternal anemia was significantly associated with effect on birth weight. Also Hb > 13 g/dl was also associated with an increased risk of low birth weight.