  We report a magnetoresistance study of the superconducting ferromagnet UCoGe.
The data, taken on single-crystalline samples, show a pronounced structure at
$B^* = 8.5$~T for a field applied along the ordered moment $m_0$. Angle
dependent measurements reveal this field-induced phenomenon has an uniaxial
anisotropy. Magnetoresistance measurements under pressure show a rapid increase
of $B^*$ to 12.8~T at 1.0~GPa. We discuss $B^*$ in terms of a field induced
polarization change. Upper critical field measurements corroborate the unusual
S-shaped $B_{c2}(T)$-curve for a field along the $b$-axis of the orthorhombic
unit cell.
