Great thread :)
I'm 26, I had been TTC for about 5 years and decided to lose weight last year to increase my chances/be a suitable weight for asking for assistance. Got from a BMI of 53 down to around 40 last year before finding out I had concieved naturally.
My BMI at booking in was 41 (the day after boxing day so inflated with Christmas eating). I lost weight in Jan/early Feb due to healthy eating/sickness I think I got down to 38. I'm now 30 weeks and my weight has got back up to what it was around booking in. That said, I haven't been eating as healthily as I could so I do think it would have been possible for me to keep my weight down a little longer.
In terms of care, I've been seen by my local midwives connected to the MLU so far. They have been great and reassured me that weight alone wouldn't stop me from birthing with them. A consultant looked over my notes earlier in pregnancy and only made the commented on them that she'd see me towards the end of pregnancy to discuss birth options. My midwives told me that this was standard, and that I'd be told the risks (such as increased risk of PPH) but that I'd still be able to choose the MLU if I wanted.
I saw an anesthist (sp?) earlier in pregnancy because of my BMI (again the routine proceedure). She just talked about pain relief options, and checked my back and mouth to make sure there weren't issues that would make anesthisia difficult. I was told that if I wanted an epidural I'd need to ask for it early so they had more time to site it, and that in the event of an EMCS if I didn't already have a epidural there was an increased risk that I'd need to go under GA. I wasn't fussed by this however as I planned to give birth at the MLU so knew if I ended up in CLU that it would be because of medical necessity.
Unfortunately, 2 weeks ago I gave a urine sample that showed I had a UTI, and they sent the sample off and it came back positive for group b strep. That's really going to change my birth plans, as I'll need IV antibiotics during labour. I think that's just one of those things and is unconnected to my weight.
As part of my antenatal care the midwives have started weighing me at appointments. I'm not too concerned about this as I weight myself anyway, but I guess others could find it stressful. I'm really happy with how the MLU have dealt with my high BMI though I am now concerned about how I'll be treated in labour at the CLU.
I think that once the baby is here and we've recovered from the birth and established breastfeeding, I'd like to start losing weight again. I had it in my mind last year when I was losing weight that I was doing it so I could have a healthy pregnancy and birth and be the kind of active mum I'd like to be. So in a way, when I got pregnant early (i.e. before I was down to my target weight) I was a bit disappointed that I would still be a larger women for my pregnancy, even though this baby was much longed for. I didn't believe I could get pregnant without help (I mean we had been TTC for years) so it didn't occur to me to stop TTC whilst I lost weight, and I think even if it had, I wouldn't have done it because we wouldn't have wanted to deny the merest chance of getting pregnant. :(
I'd like to make sure that I start any future pregnancies at a healthier weight. That said, there really isn't any point having a go at larger women who are already pregnant. As the advice is to not diet, there is little that we can do about it other than try to make sure we're in better health next time.
I speak only for myself about the health thing. I know I wasn't healthy, but I totally believe that some healthy people are larger than others and don't necessarily fit nicely into the normal BMI range.
I agree about the lack of suitable maternity wear for larger women. I have mostly stuck to the larger sizes of clothes that I hadn't thrown away after losing weight and stretchy waistbands. I did treat myself to over the bump maternity jeans (size 22) and a maternity swimming costume from NEXT - had to use their online store as the nearest one doesn't have a maternity section.
Interestingly enough, I wish I had gone for a size 20 in the mat jeans. Although I had just got down to a size 22 before pregnancy, much of my excess was in the belly area, which is covered by the stretchy bump panel, so they don't stay up very well, I think my hips etc which should hold the jeans up are maybe a size down. Plus I did lose weight in the early months of pregnancy which might have altered my size too.
Totally understand the concern about cost though. Although £30 isn't too unreasonable for my jeans, I don't think I've ever paid that for a non-maternity pair cheapskate 
All the best with your pregnancies ladies xx Thanks for the thread :)