Is fetal insulin secretion affected by fetal hypoxia?

Fifty-five pregnant Rhesus isoimmunized women were subjected to fetal blood sampling or fetal blood transfusion on 135 occasions. Glucose and C-peptide concentrations were measured in fetal blood, in addition to the routine investigations for complete blood count, blood gases and lactate concentration, in order to investigate whether fetal insulin secretion was affected by hypoxia from fetal anemia. We found a strong relation between the concentration of C-peptide and gestational age at sampling (r = 0.53, P less than or equal to 0.000001). Multiple regression analysis also demonstrated that glucose (P less than or equal to 0.0051) and lactate (P less than or equal to 0.0003) also affected the concentration of C-peptide. We were unable to find any relation between C-peptide concentrations and blood gas variables. We conclude that fetal insulin secretion, measured as C-peptide concentration in fetal blood, is not affected by hypoxia from anemia as long as hemoglobin concentration remains within the range 2.1-14.8 g/dl).