My question, however, is why juice at all? Why not just eat the actual
fruit? The fiber of whole fruits especially would be helpful in
ameliorating a common complaint of pregnant women.

This would be my answer, not that you were asking me, which is that I don't
find it easy to eat fruit, in the normal course of things I don't both with
juice, but I probably should, it's supposed to be ok to count it as one
portion a day and if I was drinking juice, fresh get's more of the fibre and
other goodness into it.

Cheers

Anne