  We derive new upper limits on the ellipticity of pulsars whose braking index
has been measured, more tightening than those usually given, assuming that both
a gravitational torque and an electromagnetic one act on them. We show that the
measured braking indexes of pulsars are recovered in this model. We consider
the electromagnetic torque both constant and varying with time. At the same
time constraints on the pulsars initial period and on the amplitude of the
gravitational waves emitted are obtained.
