Joyce M,
                Glad you brought up stress and breath-holding, and how this
delays let-down. Some women do hold tension during pumping or if they have
had to work on good position and latch. I use a technique similar to your
"big deep breath and blowing out" to trigger muscle relaxation. I suggest to
the mom that she take a deep relaxing breath ( as I take a deep breath),
relax those shoulders ( as I do a light fingertip stroke downward on her
shoulders), close hers eyes and think about rivers of milk flowing towards
her nipples ( as I do a downward stroke in the air just above her skin from
her shoulders toward nipples - sort of a "therapeutic touch" technique). This
consistently results in a smile and an obvious release of tension. In
prenatal breastfeeding or childbirth preparation class or at the bedside
postpartum, these techniques can be included in the discussion and practice
for the support person role in facilitating let-down specfically,  and
breastfeeding in general. Would like to hear of other ideas!
-Deborah Tobin