Jay, I nursed my son through my pregnancy. He was 3 1/4 when she was born.
He didn't slow down at all, even though there was definitely a reduction
in milk by I'd say about 7-8 months, and only colustrum for at least
the last 3 weeks or so. Also, my milk didnt come in until after my daughter
was born, although it only took about 2 days (sorry I can't remember
exactly) What I do remember is that nursing really started to hurt as
he quickly emptied my breast. Felt like the nipple was compressing on
itself because there was nothing coming out... hard to describe. So, I
was uncomfortable, but he didn't seem to mind anything. in fact, I tasted
the colostrum (is that weird?)to see, and it was awful tasting, bitter,
I still can't figure out how he could stand it. It did seem that he
 would often drink juice after nursing as if you wash his mouth out...
The cutest thing was when my daughter was 10 days old and my son nursed
around lunch time, then I asked if he wanted to go eat. He answered
"I can't believe it Ema (Mom in Hebrew) there's so much milk I'm full
up to here" and he indicated his neck. My son nursed mostly for the
pleasure of it, not food, so pregnancy changes made no difference. I
suppose different kids respond differently. hope this helps
Dalia