  The parity-non-conserving (pnc) asymmetry in \vec{n} + p \to d+\gamma at
thermal energies has recently been calculated using effective field-theory
methods. A comparison of this calculation with much more elaborate calculations
performed in the 70's is made. This allows one to assess the validity of this
new approach as presently used. It is found to overshoot the almost exact
calculations by a factor close to 2 for the contribution involving the ^3S_1
component of both the initial and final states. This is much larger than
anticipated by the authors. This discrepancy is analyzed and found to originate
from the over-simplified description of the deuteron and capture states which
underlies the new approach. The claim that earlier determinations of the sign
would be in error is also examined. It is found that the sign discrepancy is
most probably due, instead, to the fact that the pion-nucleon interaction
referred to by the authors corresponds to a parity-non-conserving potential
with a sign opposite to what is currently used. Some estimates and constraints
relative to the pnc piNN coupling, h^1_{\pi}, which the above asymmetry is
dependent on, are reviewed. Further details are given in an Appendix.
