My girls never weaned while pregnant although I do believe my supplied dropped when I was pregnant with DD3 but it didn't seem to bother DD2. I was still tandem feeding for the first few months of this pregnancy and both girls were content but it was just too sensitive so I had to wean my 3yo for my own comfort, but have continued feeding my youngest. As for colostrum, I have no idea when it came in but I know that it was colostrum the day my babys were born as I had to exclusivly express for all of my newborns due to them being in NICU.