  On the basis of microscopic theory it is demonstrated how the coupling
between the electrons by means of magnetization fluctuations in ferromagnetic
metal with orthorhombic symmetry gives rise equal spin pairing superconducting
state with general form of the order parameter dictated by symmetry. The strong
upturn of the upper critical field along $b$-direction above 5 Tesla in UCoGe
is explained by the increase of pairing interaction caused by the suppression
of the Curie temperature by magnetic field parallel to b-axis. It is proposed
that similar phenomenon at much higher field must take place also for the field
directed along the magnetically hardest a-direction.
