To investigate the association between maternal iron status at the third trimester and fetal birthweight, maternal serum iron, ferritin, total iron-binding capacity (TIBC), and complete blood count values were measured at 36-weeks gestation. Delivery database on mothers who delivered babies at Chungbuk National University Hospital between January 2008 and March 2013 was extracted. A total of 353 uncomplicated term babies were analyzed using hierarchical regression and ANCOVA. Maternal age (standardized regression coefficient β=0.115, P<0.05), height (β=0.108, P<0.05), BMI (β=0.210, P<0.001), and gestational age (β=0.298, P<0.001) were significantly associated with birthweight. However, birthweight was not associated with maternal iron parameters. After adjusting for maternal age, height, BMI, and gestational age, babies born to mothers with lower mean values of hemoglobin, hematocrit, and serum ferritin were heavier than those born to mothers with higher values. Babies born to lower hemoglobin (11 g/dL) mothers were heavier than those born to higher hemoglobin (12 g/dL) mothers. However, birthweight was not significantly different between mothers with 10 g/dL or 13 g/dL of hemoglobin. Comparing birthweight according to 30 ug/dL of serum iron, 360 ug/dL of TIBC, 15 ng/mL of serum ferritin, and 10% transferrin saturation, babies born to mothers of the lower group were heavier than those born to mothers of the higher group. Therefore, maternal serum iron status at the third trimester seems to not be associated with birthweight.