As an update, it looks at the moment like things are headed in a positive direction. According to my friend: on Saturday, the day after the surgery, the ultrasound showed 3 cm of amniotic fluid, and on Monday afternoon it showed 6 cm, which is a good sign. ("Normal" is apparently 12 cm or above.) They are in the process of moving the mother from IV medications to oral.
Although it looks like things are moving in the right direction, they are by no means anywhere near 'out of the woods' yet. Your continued prayers for all of them will be greatly appreciated. Thanks.