Serum ferritin and cobalamin in growth retarded fetuses

To examine fetal and maternal serum cobalamin and ferritin concentrations in pregnancies complicated by fetal growth retardation.

Harris Birthright Research Centre for Fetal Medicine, King's College Hospital Medical School, London.

Cross sectional study.

Fetal blood samples obtained by cordocentesis from 20 growth retarded fetuses at 26 to 36 weeks of gestation. Maternal venous blood was also collected and serum ferritin and cobalamin concentrations were measured by radio-immunoassay in the fetal and maternal samples.

In the growth retarded group, the mean fetal serum concentration of cobalamin was higher than the normal mean for gestation (t = 3.27, P < 0.01), and this increase was significantly associated with fetal acidaemia (r = -0.686, P < 0.001) and erythroblastosis (r = 0.731, P < 0.001). In contrast, the fetal to maternal ferritin ratio was significantly reduced; there was a nonsignificant decrease in fetal serum and an increase in maternal serum ferritin concentration. There was an association between fetal serum ferritin concentration and erythrocyte count (r = -0.612, P < 0.01).

In placental insufficiency, as in postnatal starvation and Kwashiorkor syndrome, uptake and storage of cobalamin by the fetal liver may be impaired. The decrease in fetal to maternal ratio of ferritin could be the consequence of impaired placental perfusion.