You'll most likely get an answer on whether or not it will be prioritised in a few weeks, but it's not likely to be granted. The bar is set very high when it comes to things like this for obvious reasons.
Pregnancy isn't sufficient in and by itself. There has to be medical reasons of importance (documented inadequate hospital facilities) or practical reasons of great importance.
http://www.udi.no/Norwegian-Directorate-of-Immigration/Oversiktsider/Case-processing-times/Can-I-request-for-priority/
Keep in mind, that even if you do fall into the category of having insufficient medical services, a few weeks is still rather unlikely. Not only does the permit itself have to be processed (this can theoretically go fairly quickly if all the paperworks is in order), but the grounds for prioritising have to be assessed as well. Add to that the fact that this is Norway, and people are going to start going on Christmas break next Friday, that leaves 6 business days. Some people will probably be in on weekends, but still...not a lot of time.
Realistically, unfortunately, you're looking at the average wait time of 4-6 months. If you can prove there are exceptional circumstances above and beyond pregnancy, then you could expect the wait to be around a month given the time of year. There are a lot of days all govt offices will be closed, and there won't be a full staff from next Friday until the first week of the new year.
That said, if you do have exceptional circumstances, get that documentation in immediately. This paperwork can take time just going from the embassy to UDI. They don't have the greatest system in place, so that alone can easily take a week (but, they really do try to get things sent quickly. They know these things are extremely important).
I'm really sorry I don't have better news. I have friends waiting on fiancee permits and family reunification. I know very well how hard it is. Good luck with it all. I hope it goes quickly for you.