I was 6mths pregnant on DS1 when we bought our house (and it needed renovating) we moved in a week before he was born. TBH I didn't find moving house that stressful, however, with DS2, we were and still are in the process of converting the loft - all manner of things happened:
Our bedroom no longer existed (we had to partition it to make a hallway and stairs to the loft) so the bedroom needed a new wall, electrical stuff full plastering, a few new floorboards, new ceiling...etc... etc...
So, we (me being 38wks preg) were sleeping on a mattress on the floor of DS1's bedroom (whose ceiling had been cracked by them doing the work in the loft....
So, when the room was ready to be decorated (39wks) there i was up ladder painting (DH was against me doing so, but I couldn't rest til it was done) What made things feel worse for me was that this was the room I had planned all pregnancy to give birth in!
Anyway....
At almost 40wks, the room was finally finished - The hallway was in the middle of still being plastered and there was and still is a massive hole with a staircase in going up to the loft (still with no wall between us and our next door neighbour - so if they wanted to come in to our house, they could - good job we have good neighbours). But at this point I was so upset - crying every day etc... that i literally chucked the plasterer out mid plastering. He was in the middle of doing the hall way upstairs when i just went up and said - please can you leave, I've had enough of the mess and this baby is gonna be coming soon and i need to clean up. (I was polite).
That was 5mths ago and nothing has been done since.
So.....
If it was me, i would be setting a deadline - write them a letter, explaining that it has already taken the 4 weeks and will be taking them 4 weeks longer than their original 2 weeks as planned. Set them a reasonable deadline in writing and say that you expect them to be finished and out by that date (working evenings if necessary). Be firm, but fair - if you go in complaining, some builders may just walk off the job, and you certainly wont want that. But you do need to let them know that it needs to be finished with now more extensions on time.
Are there any rooms that are finished that you could get in and clean already? Can you move some of the things in now, so that there is less to do when you get the final date? Can your DH get in there in the evenings and touch up the paint now? There must be a way of working around the electricians - my DH has a building firm, and its amazing what his contractors can achieve when given a deadline.
I would pu all the baby's clothes and bits into a chest of drawers and cover them with tissue to keep out the dust and move the chest with the things already in - then they are already washed and folded ready for your new arrival.
Finally (sorry its taken me so long) I hope that everything sorts itself out for you, that the move goes smoothly and that you have a great birth. Good luck, and let us know!