Relative fetal hypoxia as a contributing factor to fetal macrosomia in diabetic pregnancy.

Results from Ogata et al (5) have shown that the initial increase in fetal size in the macrosomic neonates of diabetic mothers occurs after approximately 26 weeks gestation, and that a further more dramatic increase occurs at approximately 34 weeks until term. It is proposed that the initial increase is caused by fetal hyperinsulinism (Pedersen Hypothesis), and that the latter increase results from an induced relative fetal hypoxia. It is suggested that the mechanism responsible for the latter increase in fetal size is an increase in the amount of fetal glucose which is metabolised through the hexose monophosphate shunt pathway.