I am 5'10" and 313 lb. and carry my weight quite well and I feel on the edge about the weight loss issue. I have been as skinny as 150 lbs. when I had my first child and my weight gradually crept up and I continued to get pregnant. Although, I am not saying that being my size is acceptable by no means, I think that we need to be as healthy as possible when thinking about having little ones.
I do plan on starting a weight loss routine while I am pregnant like I always have, but when I dropped from 313 to 280, my periods stopped coming and I had to delay my first IVF cycle due to having to take Prometrium. I think the goal is just to be healthy!