  We suggest that neutron stars experienced at birth three related physical
changes, which may originate in magneto-rotational instabilities: (i) an
increase in period from the initial value P_0 to the current value P_s,
implying a change of rotational energy \Delta E_rot; (ii) an exponential decay
of its magnetic field from the initial value B_0 to the current surface value
B_s, implying a change of radiative energy \Delta E_rad; and (iii) an increase
of space velocity from the initial value v_0 to the current value v, implying a
change of kinetic energy \Delta E_kin. These changes are assumed to be
connected by \Delta E_rad + \Delta E_kin =\Delta E_rot. This means that the
radiation loss and increase of kinetic energy are both at the expense of a
rotational energy loss. It is shown that this energy conversion occurs during
times of order of 10^(-4) s if the neutron stars are born with magnetic fields
in the range of 10^(15)-10^(16) G and initial periods in range 1-20 ms. It is
shown that the birth accelerations of neutron stars are of the order of 10^(8)
g.
