So, here's my favorite maternity clothes trick for this pregnancy. Go to the sales racks and find some incredibly discounted tube dresses with a large elastic top to fit over the chest area. Something like this:
These would be strapless, fairly short, and definitely immodest if worn as intended. However, if the chest band is worn around your burgeoning belly, it becomes a modest skirt that will see you through the early weeks of pregnancy, the ginormous weeks toward the end, and back down through the postpartum period. Enjoy!