Effects of fetal insulin secretory deficiency on metabolism in fetal lamb.

Fetal insulin secretion may be of importance in determining both fetal metabolic rate and glucose homeostasis in the resting state. To investigate this question, streptozocin (STZ) was injected into 10 late-gestation fetal lambs, and the effects of STZ on fetal pancreatic insulin storage and secretion, fetal metabolic rate, and umbilical glucose uptake were then studied. Fetal STZ injection caused a relative fetal hyperglycemia by 24 h after injection. Fetal hyperglycemia reached a maximum by 72 h and persisted for at least 10 days after injection. Neonates delivered after fetal injection were frankly diabetic. Fetal STZ injection was associated with complete suppression of both glucose- and tolbutamide-stimulated insulin release, although no changes in peripheral insulin concentration were observed when compared with controls. Fetal pancreatic insulin content was only 13% of that expected on the basis of gestational age. In a subgroup of 7 STZ-treated fetal lambs, fetal hyperglycemia was related to decrements in umbilical venoarterial difference of glucose, umbilical glucose uptake, and glucose-O2 quotient. No changes in maternal glucose homeostasis or in fetal O2 consumption were noted. The data suggest that deficient fetal insulin storage and secretion are associated with a decrement in exogenous fetal glucose entry but not in fetal metabolic rate. Whether the observed fetal changes relate to enhanced endogenous fetal glucose production with a passive decrease in maternofetal glucose transfer or are simply due to a decrease in overall fetal glucose utilization is not known. It is speculated that a quantitative decrease in pancreatic insulin secretion is responsible for the observed changes.

The fetal biophysical profile in patients with premature rupture of the membranes--an early predictor of fetal infection.

A modified fetal biophysical profile (nonstress test, fetal movements, fetal breathing movements, fetal tone, amniotic fluid volume, and placental grading) was serially assessed in 73 patients who presented with premature rupture of the membranes and were not in labor. The last study before delivery was compared with the outcome of pregnancy. The relationships between individual variables and combinations of variables (biophysical scoring) and the outcome of pregnancy--as reflected by the development of chorioamnionitis and/or neonatal sepsis--were determined. These data suggest that the fetal biophysical profile is a useful tool for evaluating patients with rupture of the membranes. Rupture of the membranes by itself does not alter the biophysical scoring of the healthy fetus; however, a low biophysical score (less than or equal to 7) was a good predictor of impending fetal infection in patients with premature rupture of the membranes.