The apparent effect of iron supplementation on serum selenium levels in teenage pregnancy

Numerous studies have suggested a significant role of selenium in the prevention of gynecological carcinoma. These were epidemiological and prospective in humans and therapeutic in laboratory animals. However, no studies have been reported regarding the normal serum selenium levels during pregnancy. The maternal total blood volume increases 30-50% during the second and third trimesters, resulting in lower measured serum levels for those metabolites, which are not increased significantly during pregnancy. A longitudinal study of the serum selenium levels in teenage pregnancy during the last two trimesters and 3 mo postpartum showed progressive elevation from 49 +/- 7 microg/dL after the 32nd week of pregnancy to 114 +/- 7 microg/dL at term, which was statistically significant (p < or = 0.001). Prenatal supplementation with 18 mg of iron per day prevented this elevation. The results of this study suggest that serum selenium levels in women normally double during pregnancy and this doubling is prevented by the minimal daily supplementation of 18 mg of iron, which may be due to increased absorption of selenium into the erythrocytes and incorporation into the glutathione peroxidase enzyme.