Studies of the electrical resistivity were carried out under applied hydrostatic pressures up to 20 kbar and in the temperature range from 1.5 K to room temperature. The pressure dependence of the magnetic-ordering temperatures and the suppression of spin fluctuations in the paramagnetic temperature regime have been deduced from the variation of characteristic features in (T, P). Grüneisen parameters of the magnetic-ordering temperature T C and the spin-fluctuation temperature T SF have been obtained and discussed with respect to a pressure-induced destabilization of the itinerant d subsystem. Finally, as the measurements are performed under hydrostatic conditions, a possible change in the character of the magnetic phase transition from first towards second order has been investigated. ͓S0163-1829͑98͒02405-9͔