In this instance it would be your bridesmaid’s decision as to what she you would like to do with regards to sizing of her bridesmaid dress, my advice is to have the dress made slightly bigger than her pre pregnancy UK dress size/body measurements. We would need the measurements for this dress 8 WEEKS before your wedding date, and you will receive the dress 4 weeks before your wedding allowing time for any potential alterations. If your bridesmaid has told you her amazing news early on in her pregnancy it is best to consider taking her body measurements before she starts to show so you have a guideline (if she is comfortable with this) and then 8 weeks before your wedding you can both decide if she would like to go off the measurements you already took or if she wants to increase or decrease any of the measurements.
We require 4 weeks production lead time on single dresses.