Hemodynamic [heart rate, systolic and mean blood pressure] changes. The rate of placental transfer of dexmedetomidine . Apgar score (1 and 5 minute) after delivery. The umbilical cord venous and arterial blood gases analyses. The sedation of Dexmedetomidine. The incidence of the major complications (respiratory, cardiovascular events, nausea, vomiting and other adverse reactions).