I recently did a search on this (for a book of mine on PND - actually
'recent' is about a year ago so this is not red hot) but my recollection
(off top of head)  is that oestrogen therapy has been evaulated as
treatment for severe PND, but not as a prevention, and that studies are
still awaited that will confirm its safety and effectiveness for mild to
moderate PND.

I did not come across any studies that looked at its effect on bf.

I would share Pamela's caution, just on common sense grounds. Giving any
hormone at the start of bf is a very big deal indeed, and should be done
with trepidation.

Heather Welford Neil
NCT bfc Newcastle upon Tyne UK