Newton polygons and families of polynomials

We consider a continuous family (f_s), s[0,1] of complex polynomials in two variables with isolated singularities, that are Newton non-degenerate. We suppose that the Euler characteristic of a generic fiber is constant. We firstly prove that the set of critical values at infinity depends continuously on s, and secondly that the degree of the f_s is constant (up to an algebraic automorphism of ²).Mathematics Subject Classification (2000): 32S20 (Primary); 14M25 (Secondary)