I was gone for four months with my pregnancy a couple of years ago. I would keep the lessons going if possible. Could you get a basic curriculum that the sub could follow, so that you don't have to create lessons while you are out? You will need time to be home with the baby and forget about school for awhile.
I would lock up cabinets that you would rather the kids or a non art teacher not get into. I found out that the Booster Club meetings that were held in my room were using my expensive watercolor paper for students to draw on while their parents met.