Effects of ethanol on the circulation and acid-base balance of pregnant sheep.

Nine infusions of 15 cc/kg/120 min of 9.5% ethanol were administered to 4 chronically catheterized ewes, at 109-135 days' gestation. Stabilization periods ranged from 6 to 28 days postoperatively. Maternal and fetal concentrations of ethanol were almost identical (r = 0.9925), with peak levels of 122 +/- 20 mg/100 ml (mean +/- 1 SE) and 121 +/- 19 mg/100 ml, respectively, at the end of infusion. Maternal pH decreased from 7.50 +/- 0.02 to 7.44 +/- 0.02 (P less than 0.005) at 120 minutes. Maternal glycemia increased from 76 +/- 14 mg/100 ml to 162 +/- 23 mg/100 ml (P less than 0.005) at 120 minutes. Maternal heart rate, blood pressure, PO2, O2 content, PCO2, and bicarbonate remained unchanged. Fetal PO2 increased during and following infusion from 18.9 +/- 0.9 mmHg to 22.0 +/- 1.0 mmHg (P less than 0.005) at 180 minutes. Fetal blood pressure increased from 51.3 +/- 3.1 mmHg to 53.7 +/- 3.3 mmHg (P less than 0.01) at 30 minutes. Fetal pH, PCO2, glucose, and lactate levels remained unchanged. The authors conclude that ethanol crosses the sheep placenta readily, causes maternal acidosis and hyperglycemia, and increases fetal PO2, blood pressure, and heart rate without any effects on fetal acid-base status.