The group I use (Fielding, Ren, etc in NYU) do not at all believe in automatically unfilling all pregnant bandsters. They only do so if there's a reason to believe the baby is not getting enough nutrients/growing enough.
I am 11 weeks pregnant and had gained nothing and was throwing up a lot so they took out 1 cc BUT promised me they would put half of it back in a month if I felt it was necessary (I guess if I suddenly gained an insane amount of weight).
At this point I feel very little restriction but am thrilled to not be throwing up all day anymore. I gained about 2 lbs since the unfill (around 2 weeks ago) and at this point am leaning towards leaving things as is (if only the heartburn would go away. . . )
I think if you are gaining too much and are constantly hungry, a small fill is not out of order.
