Gender difference in cord serum ferritin concentrations.

We measured cord serum ferritin concentrations in a total of 255 infants (116 females and 139 males), and evaluated the association between these values and various neonatal as well as maternal characteristics. The mean ferritin concentration in females (166 +/- 110 microg/l) was significantly higher than that in male infants (123 +/- 77 microg/l). The gender differences in ferritin were significant within groups of infants with fetal growth restriction, those who weighed <3,000 g, those whose mothers were African Americans or <25 years old. Maternal serum ferritin concentrations at 36 weeks of gestation significantly correlated with cord serum ferritin of male infants (r = 0.32, p < 0.001), whereas the association was not significant for females (r = 0.09, p > 0.41). Although the mechanism of the gender difference is unknown, it may be important to consider the sex of neonates when evaluating their iron nutriture immediately after birth.