Predicting the bump: Ordering for a pregnant bridesmaid

*Sigh* Warning, this is a long post, but if you can hang in there, I'd appreciate any advice you can give. The topic? The bridesmaid dresses. On a good note, three of my four bridesmaids have purchased their gowns. I told them they can pick any dress from the Eden Bridesmaids line, just as long as it's tea length, satin and the color amethyst (the closest shade to our purple). I thought that left them enough freedom to find a dress that worked for them...but I suppose I could have given them a little more...
Here's the color:

My MOH will be rockin' this dress:

My Matron of Honor chose this lovely dress::

And my third bridesmaid chose this hot number:

Love the back!

They each purchased their gown from Netbride.com, where they got a sweet deal for $96 for each gown (Not including shipping).

But as you may know from a previous post, one of my bridesmaids is pregnant. I found out after my bridesmaids ordered their gowns. We had been putting off finding the fourth dress for awhile because she was ill during a very difficult first trimester (morning sickness, nausea, migraines, the works). Now she's feeling a little better, we're hitting another snag: finding her dress.

 Eden does have a maternity bridesmaid line but the pickings are slim. My bridesmaid wants to stay with Eden just so she won't look too different from the other girls. The only dress in satin is this dress:

My bridesmaid was leaning toward this dress because it's satin, and she could easily cut the hem to make it tea length. But alas, the dress doesn't come in amethyst.

We looked at the other maternity dresses, but they only come in chiffon:

At this point, I think chiffon is the best choice for her, and the dress will be really nice when it's hemmed to tea length, but we're not sure about how different the colors from satin to chiffon would look. One other option is that she can order satin fabric in amethyst from Eden and have the dress custom made. But we're running out of time (wedding is in four months!) and my bridesmaid is a busy girl (she's a resident doctor). I don't want her to feel pressured into settling for a dress and I don't want her to feel like a burden either (she's not, I'm more annoyed that there aren't many great and affordable maternity options out there). So I told her to pick a dress she really wants. I don't care what fabric it is, and it doesn't have to be the exact shade of purple.

But I think she really wants to stick with Eden. If she does pick a maternity dress from Eden, the next issue is "What size?" The frustrating part is that no one seems to know or can give a good answer (blank stares and crickets every time we ask someone at a bridal shop). Every woman's body is different, and how she grows during pregnancy always varies. This is her first child so she has no idea how big she will get. Since we're looking at dresses with high waists and flowing skirts to accommodate the hip and tummy area, we're trying to figure out the best bust size for her.

Eden maternity size charts go from small to 1X. Right now she's three months along, and will be 7 months pregnant by the time of the wedding. Right now, she's just three inches smaller than an XL (would that be enough room?), but 7 inches smaller than a 1X (is that too big?). My aunt, a seamstress, said she should order big because it's easier to take in than let out, but ordering too big could be a tough alteration job (more time, more money)

So what now? From what I can gather, and what people tell me, here's what I found:

* Order 2 sizes up from pre-pregnancy size. It's always easier to take in than let out the seams.

* If you will be 5 months along or less, you can probably get away with ordering a larger regular bridesmaid dress .

* Since my bridesmaid will be in her third trimester by the time of the wedding, it will be best to order a maternity gown.

* Empire waist styles are always the most flattering for pregnant women. Flowy fabrics like chiffom or silk shantung are best.

If you have any other tips or advice for ordering for a pregnant bridesmaid, let me know! We can definitely use it!