Effects of maternal glucose loading upon induced fetal distress

Glucose and insulin requirements during labor and delivery: the case for normoglycemia in pregnancies complicated by diabetes

OBJECTIVE

To present protocols for maintaining normoglycemia during labor and delivery in order to achieve optimal outcomes of pregnancy in women with diabetes.

RESULTS

Labor has a glucose-lowering effect. In the case of women with insulin-requiring gestational diabetes, no additional insulin is needed with the onset of labor; sufficient glucose should be infused to keep such women from becoming ketotic from the pronged period of starvation. Likewise, protocols derived from glucose-controlled insulin infusion studies reveal that women with type 1 diabetes require no more subcutaneously administered insulin on the morning of an induction of labor or at the onset of spontaneous labor. The intravenously administered solutions should be started with isotonic saline or electrolyte solutions. As soon as active labor is achieved, the solutions should be switched to a glucose-containing fluid and administered at a rate of 2.55 mg/kg per minute.

CONCLUSION

Labor is a form of exercise and thus obviates the insulin requirement in women with all types of diabetes, but it also necessitates an eightfold increase in glucose substrate in order to prevent maternal hypoglycemia and ketosis. The literature presents clear evidence that neonatal hypoglycemia is directly related to maternal hyperglycemia during labor and delivery. Thus, protocols for maintaining normoglycemia during labor and delivery are necessary to achieve optimal results.

Enhanced glucose metabolism and impaired placental function in hypoxic pregnant rats

Glucose metabolism using 2-deoxy-2-[18F]fluoro-D-glucose [( 18F]FDG) was studied in experimental hypoxia (10% oxygen concentration) of pregnant rats with special attention given to the placental function. After an i.v. injection of [18F]FDG, the uptake of 18F increased with time in the maternal brain, placenta and fetus of control rats. In the hypoxic condition, the uptake in these tissues was enhanced significantly, especially in the maternal brain and fetal heart, brain and lungs. A double-label autoradiography with [18]FDG and [14C]iodoantipyrine [( 14C]IAP) was performed to elucidate changes of the placental function in the hypoxic condition. The [18F]FDG image revealed a higher accumulation in the maternal side of the placenta of a control pregnant rat than in its fetal side. [18F]FDG uptake increased in the fetal brain and heart of hypoxic rats. The [14C]IAP image demonstrated that in the control rat there was a clear border zone on the maternal side of the placenta with very low permeability into the fetus. On the other hand, a high and heterogenous accumulation in both placenta and fetal organs was shown in hypoxic rats. We interpret this data to suggest that in a hypoxic condition the function of the placenta as a barrier system is impaired.

Feto-maternal consequences of high-dose glucose infusion during labour

The effects on the fetus of high doses of glucose given to the mother in labour to correct maternal ketonuria were investigated. Three groups of patients were compared: one group received 1 litre of 10% (w/v) glucose intravenously over 1 h, the second group received 1 litre of 0.9% sodium chloride solution intravenously over 1 h and the final group had no supplementary infusion. It was observed that whereas glucose administration rapidly corrected maternal ketonaemia, there was a significant fall in pH and a rise in lactate in fetal blood. These effects were not observed in the other two groups. It was concluded that the use of high doses of intravenous glucose in labour should be avoided.