OBJECTIVE: Sideropenic anemia is a common pregnancy disorder. The relationship between anemia and adverse pregnancy outcome are contradictory and it is related to the severity of the hemoglobin deficit. The aim of the study was to evaluate the relationship between maternal mild anemia at third trimester of pregnancy, fetal birth weight and fetal gender. STUDY DESIGN: A retrospective study including 1131 single physiological term pregnancies was conducted. According to maternal Hb levels during the third trimester, pregnant women enrolled, were divided in 2 groups: Group A (n = 156) with Hb≤11 g/dl and Group B (n = 975) with Hb≥11,1 g/dl. RESULTS: Maternal characteristics, gestational age at delivery, Apgar score and post-partum hemorrhage were similar between groups. However, when neonatal sex was considerate, female newborns of anemic women had a higher birth weight (p = 0.01). Moreover anemic women showed a significantly higher rate of emergency cesarean section (p = 0.006) in particular when the newborn was a male (p= 0.03). CONCLUSION: Maternal mild anemia in third trimester of pregnancy correlates with fetal birth weight, influencing fetal growth and delivery outcome on the basis of fetal gender. Even thought, the reason of this phenomenon are still unknown, these new data may represent a novel parameter to add significant prognostic information in relation to maternal mild anemia and neonatal outcome.