For what it's worth-
I don't have any statistics, and I understand the medical concerns but
anecdotally I have heard of mothers being able to express after many
years.  The way I understand it is that the important difference is
spontaneous discharge or a few drops of something when an actual attempt
is made.  The last time this happened to me I was 18 years post-weaning!
My doctor did a prolactin level and said that there was no concern.  I
have since had normal mamograms and sonogram.

Sarah Friend Barnett   LLLL, IBCLC
Bronx (New York City), NY  -  [log in to unmask]
" You are not obliged to finish the task,
 neither are you free to neglect it."       R. Tarfon